Students must start practicing the questions from CBSE Sample Papers for Class 10 Science with Solutions Set 1 are designed as per the revised syllabus.
CBSE Sample Papers for Class 10 Science Set 1 with Solutions
Time: 3 Hours
Maximum Marks: 80
General Instructions:
- This question paper consists of 39 questions in 5 sections.
- All questions are compulsory. However, an internal choice is provided in some questions. A student is expected to attempt only one of these questions.
- Section A consists of 20 objective type questions carrying 1 mark each.
- Section B consists of 6 Very Short questions carrying 02 marks each. Answers to these questions should be in the range of 30 to 50 words.
- Section C consists of 7 Short Answer type questions carrying 03 marks each. Answers to these questions should be in the range of 50 to 80 words.
- Section D consists of 3 Long Answer type questions carrying 05 marks each. Answer to these questions should be in the range of 80 to 120 words.
- Section E consists of 3 source-based/case-based units of assessment of 04 marks each with sub-parts.
Section – A
Select and write the most appropriate option out of the four options given for each of the questions 1 – 20.
There is no negative mark for incorrect response.
Question 1.
Identify the product which represents the solid state in the above reaction. [1]
(a) Barium chloride
(b) Barium sulphate
(c) Sodium chloride
(d) Sodium sulphate
Solution:
(b) Barium sulphate
Explanation: When aqueous solutions of barium chloride and sodium sulphate react they give an insoluble precipitate of barium sulphate and the solution of sodium chloride. Thus, the product which represents the solid state in the above reaction is barium sulphate.
Question 2.
The colour of the solution observed after 30 minutes of placing zinc metal to copper sulphate solution is [1]
(a) Blue
(b) Colourless
(c) Dirty green
(d) Reddish Brown
Solution:
(b) Colourless
Explanation: The colour of the solution observed after 30 minutes of placing zinc metal to copper sulphate solution is colourless because zinc being more reactive than copper displaces it from copper sulphate solution and forms a colourless solution of zinc sulphate.
Question 3.
Mild non-corrosive basic salt is
(a) Ca (OH)2
(b) NaCl
(c) NaOH
(d) NaHCO3
Solution:
(d) NaHCO3
Explanation: From the given options, sodium hydrogencarbonate, NaHCO3, is a mild non-corrosive basic salt.
Question 4.
On adding dilute sulphuric acid to a test tube containing a metal ‘X’, a colourless gas is produced when a burning match stick is brought near it. Which of the following correctly represents metal ‘X’? [1]
(a) Sodium
(b) Zinc
(c) Copper
(d) Silver
Solution:
(a) Sodium
Explanation: When dilute sulphuric acid is taken in a test tube containing sodium metal, sodium sulphate is formed along with the liberation of hydrogen gas which is colourless gas. Thus, metal ‘X’ is sodium metal. The balanced chemical reaction can be represented as:
Question 5.
Which one of the following correctly represents Sodium oxide? [1]
Solution:
Explanation: From the given structures, below Lewis structure correctly represents sodium oxide:
Question 6.
An element with atomic number ……………… will form a basic oxide. [1]
(a) 7 (2, 5)
(b) 17 (2, 8, 7)
(c) 14 (2, 8, 4)
(d) 11 (2., 8, 1)
Solution:
(d) 11(2, 8, 1)
Explanation: Generally, metals form basic oxide while non-metals form acidic oxide. Metals have 1 to 3 electrons in the outermost shell whereas non-metals have 4 to 8 electrons in the outermost shell. The electronic configuration of given elements are as follows:
Atomic Number | Electronic Configuration |
7 (Nitrogen) | 2, 5 |
17 (Chlorine) | 2, 8, 7 |
14 (Silicon) | 2, 8, 4 |
11 (Sodium) | 2, 8, 1 |
Thus, element with atomic number 11 (sodium) having electronic configuration 2, 8, 1 is metal and it will form a basic oxide. Whereas, the other three elements having atomic numbers 7 (Nitrogen), 17 ; (Chlorine) and 14 (Silicon) are non-metals and hence they will form acidic oxide.
Question 7.
An element ‘M’ has 50% of the electrons filled in the 3rd shell as in the 2nd shell. The atomic number of ‘M’ is: [1]
(a) 10
(b) 12
(c) 14
(d) 18
Solution:
(c) 14
Explanation: The atomic number of silicon is 14 and its electronic configuration is 2, 8,4.
In its first shell or K shell, it has 2 electrons.
In its second shell or L shell, it has 8 electrons.
In its third shell or M shell, it has 4 electrons.
Thus, it has 50% of the electrons filled in the 3rd shell (i.e., 4 electrons) as in the 2nd shell (i.e., 8 electrons).
Question 8.
Generally food is broken and absorbed within the body of organisms. In which of the following organisms is it done outside the body? [1]
(a) Amoeba
(b) Mushroom
(c) Paramoecium
(d) Lice
Solution:
(b) Mushroom
Explanation: The process of animals feeding on dead and decaying substances or organisms for : getting energy, food and nutrition is called as saprophytic nutrition and the organisms that follow saprophytic nutrition are called saprotrophs. They are the recycler of nutrients as they release specific enzymes that act on complex organic matter and break them into smaller and simpler particles that are easily consumable by the organism. Organisms like – Mushrooms, Yeast, and Bread moulds are saprophytic. They break down food outside the body and absorb the simpler digested particles. Hence, from the given options fungi, mushroom break down food outside the body and absorb the simpler digested particles.
Question 9.
Receptors are usually located in sense organs. Gustatory receptors are present in [1]
(a) tongue
(b) nose
(c) eye
(d) ear
Solution:
(a) tongue
Explanation: Receptors are present in our all parts of the body. They detect the signals and send to the brain in the form of electrical signals.
(i) Gustatory receptors – Its function is to detect Taste. It is present in the tongue.
(ii) Olfactory receptors – Its function is smell detection. It is found in the nose.
(iii) Photoreceptors – Its function is to see. It is present in the eyes.
(iv) Phonoreceptors – Its function is to hear and balance the body. It is found in the ears.
Hence, the gustatory receptors are present in tongue.
Question 10.
A farmer wants to grow banana plants genetically similar enough to the plants already available in his field. Which one of the following methods would you suggest for this purpose? [1]
(a) Regeneration
(c) Vegetative propagation
(b) Budding
(d) Sexual reproduction
Solution:
(c) Vegetative propagation
Explanation: Plants that are genetically similar enough can be grown by the means of vegetative propagation. This method of asexual reproduction is a method of rapid propagation where the sex cells are not involved. The new plant formed is also genetically similar to the parent plant. In this type of asexual reproduction, parts of the plant like stem, roots or leaves can be used to grow new plants. Banana propagation is a type of vegetative reproduction.
Question 11.
Height of a plant is regulated by: [1]
(a) DNA which is directly influenced by growth hormone.
(b) Genes which regulate the proteins directly.
(c) Growth hormones under the influence of the enzymes coded by a gene.
(d) Growth hormones directly under the influence a gene.
Solution:
(c) Growth hormones under the influence of the enzymes coded by a gene.
Explanation: The information source for making proteins in the cell is cellular DNA. A section of DNA that provides information for one protein is called the gene for that protein. Plant height and its growth is regulated by growth hormones. Hormone production is in turn controlled by genes which control enzyme activity for hormone production.
Question 12.
A sportsman, after a long break of his routine exercise, suffered muscular cramps during a heavy exercise session. This happened due to: [1]
(a) lack of carbon dioxide and formation of pyruvate.
(b) presence of oxygen and formation of ethanol.
(c) lack of oxygen and formation of lactic acid.
(d) lack of oxygen and formation of carbon dioxide.
Solution:
(c) lack of oxygen and formation of lactic acid.
Explanation: During heavy exercise, the demand for energy is high but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes places in the muscles cells to fulfil the demand for energy. This anaerobic breakdown of glucose leads to the formation of lactic acid in muscles. The accumulation of lactic acid in muscles leads to muscle cramps. Hence, due to lack of oxygen and formation of lactic acid, a sportsman suffered muscular cramps during a heavy exercise session.
Question 13.
An object is placed in front of a convex mirror. Its image is formed : [1]
(a) at a distance equal to the object distance in front of the mirror.
(b) at twice the distance of the object in front of the mirror.
(c) half the distance of the object in front of the mirror.
(d) behind the mirror and it’s position varies according to the object distance.
Solution:
(d) behind the mirror and it’s position varies according to the object distance.
Explanation: When an object is placed in front of a convex mirror, the image is always formed on the backside of the mirror and is known as a virtual image. The convex mirror always forms an image that is smaller than the size of the object and its position varies according to the object distance.
Question 14.
When light enters the atmosphere it strikes on extremely fine particles, which deflect the rays of light in all possible directions, This is due to – [1]
(a) reflection of light
(c) scattering of light
(b) atmospheric refraction
(d) dispersion of light
Solution:
(c) scattering of light
Explanation: The earth’s atmosphere is a heterogeneous mixture of minute particles like smoke, tiny water droplets, suspended particles of dust, and molecules of air. When a beam of light enters the atmosphere it strike on such extremely fine particles, which deflect the rays of light in all possible direction due to scattering of light. As a result of this phenomenon, the path of the beam becomes visible.
Question 15.
In 1987, an agreement was formulated by the United Nations Environment Programme (UNEP) to freeze the production of “X” to prevent depletion of “Y”. “X” and “Y” respectively referred here are:
(a) Ozone; CFCs
(b) CFCs; rays UV
(c) CFCs; Ozone
(d) UV rays; Diatomic oxygen
Solution:
(c) CFCs; Ozone
Explanation: Ozone layer which protect the harmful UV radiation from reaching the earth’s atmosphere is depleting due to the usage of CFCs (Chlorofluorocarbons) Therefore, in order to protect the stratospheric ozone layer from depletion, in 1987, an agreement was formulated by | the United Nations Environment Programme (UNEP) to freeze the production and usage of CFCs (Chlorofluorocarbons).
Question 16.
Which of the following features relates to biodegradable substances? [1]
(a) Broken down by biological processes
(b) Remain inert
(c) Persist in environment for long time
(d) May harm the ecosystem
Solution:
(a) Broken down by biological processes
Explanation: The substances that can be easily broken down by the biological processes are called as biodegradable wastes. These substances are decomposed through the actions of fungi, bacteria, and other living organisms. For example : Food waste, paper, wood, cloth, cow-dung, humans and animal excreta etc.
On the other hand, the substances that cannot be broken down by biological processes are called as non-biodegradable wastes. These substances may be in solid, liquid or gaseous form. These substances are inert and simply persist in the environment for a long time or may harm the various members of the ecosystem. For example, DDT, insecticides, pesticides, mercury, plastics, polythene bags, glass, radioactive wastes. These non-biodegradable wastes are major pollutants of the environment.
Question No. 17 to 20 consist of two statements-Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, and R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Question 17.
Assertion: Rusting of Iron is endothermic in nature.
Reason: As the reaction is slow, the release of heat is barely evident. [1]
Solution:
(d) Assertion is false but Reason is true.
Explanation: Rusting is a chemical process in which iron gets converted into hydrated ferric oxide in the presence of air and water with the evolution of large amount of heat. This is known as rusting. The product so formed is called as rust.
Hence, the process of rusting is an exothermic reaction. This is because the rust-producing process between iron and damp air releases a lot of heat. FFowever, the reaction normally takes place at such a sluggish rate that the release of heat is barely evident. Thus, assertion is false but reason is true.
Question 18.
Assertion: Probability of survival of an organism produced through sexual reproduction is more than that of organism produced through asexual mode.
Reason: Variations provide advantages to individuals for survival. [1]
Solution:
(a) Both A and R are true, and R is the correct explanation of A.
Explanation: The Probability of survival of an organism produced through sexual reproduction is more than that of organism produced through asexual mode. This is because an organism produced by sexual reproduction have a greater survival rate as variations provide advantages to individuals for survival and they can adapt to various environments. Thus, both assertion and reason are true and reason is the correct explanation of assertion.
Question 19.
Assertion : A compass needle is placed near a current carrying wire. The deflection of the compass needle decreases when the magnitude of the current in the wire is increased.
Reason : The strength of a magnetic field at a point near the conductor increases on increasing the current. [1]
Solution:
(d) A is false but R is true.
Explanation: The deflection is directly proportional to the intensity of the magnetic field generated by the current carrying conductor and that magnetic field intensity is also proportional to the magnitude of the current. Which implies, the deflection of the needle is directly proportional to the magnitude of the current through the conductor. Therefore, the deflection of the compass needle should increase when the magnitude of the current in the wire is increased. Every current carrying conductor creates a magnetic field around it. The intensity of this magnetic field is directly proportional to the magnitude of the current flowing through the conductor. This means that the strength of a magnetic field at a point near the conductor increases on increasing the current. Thus, assertion is false but reason is true.
Question 20.
Assertion: Biodegradable substances result in the formation of compost and natural replenishment. Reason: It is due to breakdown of complex inorganic substances into simple organic substances. [1]
Solution:
(c) A is true but R is false.
Explanation: Biodegradable substances such as food waste, humans and animal excreta, plant products, dried leaves, grass, fruits, flowers, food wastes, wood and other remains of the death of living creature result in the formation of compost and natural replenishment. This is because complex organic substances like carbohydrates, proteins, and lipids present in these substances are converted into simple inorganic substances like hydrogen, oxygen, calcium, iron, and sodium. These inorganic substances are released back into the soil and they serve as nutrients for the growth of plants, thereby balancing the ecosystem. Thus, assertion is true but reason is false.
Section – B
Question No. 21 to 26 are Very Short Answer Questions
Question 21.
Dil. HCl is added to Zn granules.” How will you prove that chemical change has taken place here?
Support your response with two arguments. [2]
Solution:
When dil. HCl is added to Zn granules taken in a test tube:
- The colour of zinc metal changes from silvery grey to black.
- Colourless and odourless hydrogen gas is evolved which is visible as small bubbles.
Question 22.
State the post-fertilisation changes that lead to fruit formation in plants. [2]
Solution:
The post-fertilisation changes that lead to fruit formation in plants are:
- Zygote divides several times to form an embryo within the ovule.
- The ovule develops a tough coat and is gradually converted into a seed.
- The ovary grows rapidly and ripens to form a fruit.
- The petals, sepals, stamens, style and stigma may shrivel and fall off.
Question 23.
What is the purpose of making urine in the human body? Name the organs that stores and releases the urine.
OR
Why do arteries have thick and elastic walls whereas veins have valves? [2]
Solution:
The purpose of making urine in the human body is to filter out nitrogenous waste products like urea and uric acid from the blood in humans.
Organ for storage: Urinary Bladder
Organ for release: Urethra
OR
The blood emerges from the heart under high pressure and flows through arteries. Hence, to bear this pressure the arteries have thick and elastic walls. Whereas, veins only have valves to ensure that the blood flows in one direction only.
Question 24.
The refractive indices of three media arc given below:
Medium | Refractive Index |
A | 1.6 |
B | 1.8 |
C | 1.5 |
A ray of light is travelling from A to B and another ray is travelling from B to C.
(a) In which of the two cases the refracted ray bends towards the normal?
(b) In which case does the speed of light increase in the second medium?
Give reasons for your answer. [2]
Solution:
(a) When light travels from an optically rarer medium to an optically denser medium it moves towards the normal. Since nB > nA, hence the light ray will bend towards the normal on passing from medium A to B.
(b) The speed of the light will increase when the light travels from B to C, Since nC < nB and υ =(c/n), the speed of light ray will increase in the second medium i.e., medium C.
Question 25.
A piece of wire of resistance R is cut into three equal parts. These parts are then connected in parallel. If the equivalent resistance of this parallel combination is R1, what is the value of the ratio R1 : R?
OR
Refer to the image below and state how the magnetic field pattern indicates regions where the magnetic
field is stronger outside the magnet? What happens to the magnetic field when the current in the circuit is reversed?
Solution:
As resistance is proportional to the length of the wire, therefore,
Resistance of each part is \(\frac{\mathrm{R}}{3}\)
\(\frac{1}{R_1}=\frac{3}{R}+\frac{3}{R}+\frac{3}{R}=\frac{9}{R}\)
∴ R1 = \(\frac{\mathrm{R}}{9}\)
∴ \(\frac{\mathrm{R}_1}{\mathrm{R}}=\frac{1}{9}\)
Hence, the value of the ratio R1 : R is 1 : 9.
OR
The magnetic field strength is more in the region where the field lines are crowded. This means the field strength is maximum near the poles and it reduces as we go away from the poles. The direction of the magnetic field is also reversed when the current in the circuit is reversed.
Question 26.
Study the food chain given below and answer the questions that follow:
(a) If the amount of energy available at the third trophic level is 100 joules, then how much energy will be available at the producer level? Justify your answer.
(b) Is it possible to have 2 more trophic levels in this food chain just before the fourth trophic level?
Justify your answer. [2]
Solution:
(a) According to the 10 percent law, only 10% of the energy is transferred to each trophic level starting from the first trophic level or producer level. If the amount of energy available at the third trophic level is 100 joules, then only 1000 joules of energy will be available at the second trophic level and 10000 Joules will be available at the producer level or first trophic level.
(b) No, since the loss of energy at each step is so great that very little usable energy will remain after 4 trophic levels.
Section – C
Question No. 27 to 33 are short answer questions
Question 27.
The given reaction shows one of the processes to extract the metals like Iron and Manganese.
MnO2 (s) + Al(s) → Mn(l) + Al2 O3 (s) + Heat
(a) Give reason why the above reaction is known as a thermite reaction.
(b) Identify the substance oxidised and reduced in the above reaction.
(c) Give a reason why Aluminium is preferably used in thermite reactions. [3]
Solution:
(a) The given reaction is known as a thermite reaction as the reaction is highly exothermic reaction.
(b) Substance oxidised – Al(s)
Substance reduced – MnO2 (s)
(c) Aluminium is preferably used in thermite reactions as it is placed above Fe and Mn in reactivity series of metals and therefore, A1 is more reactive than Fe and Mn.
Question 28.
An element ‘M’ with electronic configuration 2 8 3 combines separately with Cl–, \(\mathrm{SO}_4^{-2}\) anions. Write the chemical formulae of the compounds formed. Predict with the suitable reason the nature of the bond formed by element ‘M’ in general. How will the electrical conductivity of the compounds formed vary with respect to ‘M’?
OR
A reddish-brown metal ‘X’, when heated in air, gives a black compound ‘Y, which when heated in presence of H2 gas gives ‘X’ back. ‘X’ is refined by the process of electrolysis; this refined form of ‘X’ is used in electrical wiring.
Identify ‘X’ and ‘Y. Draw a well-labeled diagram to represent the process of refining ‘X’. [3]
Solution:
The Chemical formulae of the compounds formed will be MCl3 and M2(SO4 )3. The nature of bond formed by element ‘M’ in general is Ionic bond because it can acquire a stable electronic configuration of neon (2, 8) by losing its three valence electrons to form M3+ cation. Compounds formed will conduct electricity in liquid or molten state but not in solid state in contrast to ‘M’.
OR
(a) ‘X’ – Copper! Cu and ‘Y’ – CuO
Question 29.
We are advised to take iodised salt in our diet by doctors. Justify it’s importance in our body. [3]
Solution:
Iodine is essential for the production of thyroxin hormone which is secreted by thyroid gland This hormone regulates fat, protein and carbohydrate metabolism in our body. Thyroxin provide best balance for growth in the body. A deficiency of iodine in the diet produces less thyroxine causing the disease called goitre in which neck will swell up due to the enlargement of thyroid gland. Hence, it is important for us to have iodized salt in our diet for the proper functioning of our body.
Question 30.
What is the probability of a girl or a boy being bom in a family? Justify your answer. [3]
Solution:
There are 50% chances that a girl may be born and 50% chances that a boy may be born. It can be explained as follows: Most human chromosomes have a maternal copy and a paternal copy. We have 22 such chromosomes. One pair of chromosomes called sex chromosomes is odd and is in not always being a perfect pair. Women have a perfect pair of sex chromosomes, both called X, (XX). But men have a mismatched pair of sex chromosomes in which one is normal sized – X chromosome while the other is a short one called Y chromosome (XY). A child receives one chromosome from mother which is essentially X chromosome. A child who inherits an X chromosome from her father will be a girl, and one who inherits a Y chromosome from him will be a boy.
Question 31.
(i) Explain why the refractive index of any material with respect to air is always greater [1 + 1 + 1]
(ii) In the figure below a light ray travels from air into the semi-circular plastic block. Give a reason why the ray does not deviate at the semi-circular boundary of the plastic block.
(iii) Complete the ray diagram of the above scenario when the light ray comes out of the plastic block from the top flat end.
Solution:
(i) The refractive index of a medium with respect to air is given by:
Since speed of light in the medium is always less than the speed of light in air, hence the above ratio is always greater than 1.
(ii) The ray of light is undergoing normal incidence at the air-plastic block interface. And for normal incidence there is no deviation.
Question 32.
(i) State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
(ii) List the factors on which the resistance of a conductor depends. [2 + 1]
Solution:
(i) Joules law of heating states that the heat dissipated across a resistor is directly proportional to the square of the current flowing through it, the resistance of the conductor and duration of flow of current.
H = I2Rt
Where, H = Heat dissipated across resistor
I = Current
R = Resistance of the conductor t = time or duration of flow of current
(ii) The resistance of a conductor depends on:
(a) Length of the conductor
(b) Area of the cross section
(c) Nature of material
(d) Temperature of the conductor.
Question 33.
Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three pin plug, whereas an electric bulb can be connected with a two pin plug? She wrote: Three pin connections reduce heating of connecting wires.
(i) Is her answer correct or incorrect? Justify.
(ii) What is the function of a fuse in a domestic circuit? [3]
Solution:
(i) Anannya’s answer is wrong because electrical appliances with metallic bodies need an earth wire which provides a low resistance conducting path to the flow of current, in case there is an accidental leakage of current through the conducting body of the appliances.
(ii) An electrical fuse in a domestic circuit is a safety device that operates to provide protection against the overflow of current in an electrical circuit. An important component of an electrical fuse is a metal wire or strip that melts when excess current flows through it.
Section – D
Question No. 34 to 36 are long answer questions.
Question 34.
(a) Rehmat classified the reaction between Methane and Chlorine in presence of sunlight as a substitution reaction. Support Rehmat’s view with suitable justification and illustrate the reaction with the help of a balanced chemical equation.
(b) Chlorine gas was prepared using electrolysis of brine solution. Write the chemical equation to represent the change. Identify the other products formed in the process and give one application of each.
OR
Raina while doing certain reactions observed that heating of substance ‘X’ with vinegar like smell with a substance ‘Y (which is used as an industrial solvent) in presence of cone. Sulphuric acid on a water bath gives a sweet-smelling liquid ‘Z’ having molecular formula C4H8O2. When heated with caustic soda (NaOH), ‘Z’ gives back the sodium salt of and the compound ‘Y.
Identify ‘X’, ‘Y, and ‘Z’. Illustrate the changes with the help of suitable chemical equations. [5]
Solution:
(a) Rehmat’s observation is correct as the hydrogen atoms are substituted by hetero atom i.e., Cl Reaction between methane and chlorine in presence of sunlight can be repersented as:
In this reaction, the chlorine free radial, abstracts hydrogen from methyl group which then riacts
with Cl2 to form chioromethane, It is can be represented as
In the above reaction, the hydrogen atoms are substituted by chlorine atom and hence this reaction is considered as substitution reaction.
(b) When electricity is passed through a concentrated solution of NaCl, also called as Brine, it decomposes and results in the formation of Sodium Hydroxide (NaOH), Chlorine gas (Cl2), and Hydrogen gas (H2). The chemical equation can be represented as:
2NaCl(aq) + 2H2O(l) 2NaOH(aq) + Cl2(g) + H2(g)
Apart from chlorine gas (Cl2), the other products formed in the reaction are sodium hydroxide or caustic soda (NaOH) and hydrogen gas (H2).
Uses
Sodium hydroxide (NaOH) or Caustic soda is used in the preparation of soaps and detergents
Hydrogen gas (H2) is used in the manufacture of ammonia for fertilizers.
OR
When ethanoic acid with vinegar like smell is heated with ethanol(which is used as an industrial solvent) in presence of cone, sulphuric acid on a water bath, a sweet-smelling liquid called ethyl ethanoate is formed. The molecular formula of ethyl ethanoate is C4H8O2. The chemical equation can be represented as:
Therefore, the substances,
X – Ethanoic acid/ acetic acid/ CH3COOH
Y – Ethanol/ Ethyl alcohol/ C2H5OH
Z – Ethyl ethanoate/ Ester – CH3COOC2H5
When ethyl ethanoate (Z) is heated with dilute solution of caustic soda or sodium hydroxide (Na), it gives back the original ethyl alcohol and sodium salt of the original carboxylic acid. Such a reaction is known as saponification reaction and it can be represented as:
Question 35.
Given below are certain situations. Analyze and describe its possible impact on a person:
(a) Testes of a male boy are not able to descend into scrotum during his embryonic development.
(b) Vas deferens of a man is plugged.
(c) Prostate and seminal vesicles are not functional.
(d) Egg is not fertilised in a human female.
(e) Placenta does not attach to the uterus optimally. [5]
OR
(a) A doctor has advised Sameer to reduce sugar intake in his diet and do regular exercise after checking his blood test reports. Which disease do you think Sameer is suffering from? Name the hormone responsible for this disease and the organ producing the hormone.
(b) Which hormone is present in the areas of rapid cell division in a plant and which hormone inhibits the growth? [3 + 2]
Solution:
(a) Sperm formation will be adversely affected because it requires a lower temperature than the body temperature.
(b) Vas deferens is a passage for transfer of sperms, so sperms will not be transferred further.
(c) When prostate and seminal vesicles are not functional, they will not add secretions for nourishment and medium for the transport of sperms.
(d) When an egg is not fertilised in a human female, it lives for about one day. Then, the thickened lining of the uterus breaks leading to discharge of blood and mucus along with the unfertilised egg. This is called menstruation.
(e) Nutrition and oxygen will not be provided to the growing embryo affecting its growth, which could have serious implications as well.
OR
(a) Sameer is suffering from a disease called diabetes. The hormone responsible for this disease is insulin and the organ producing the hormone is pancreas.
(b) Cytokinins hormone is present in the areas of rapid cell division in a plant and abscisic Acid inhibits the growth.
Question 36.
The above image shows a thin lens of focal length 5m. [1 + 2 + 2]
(i) What is the kind of lens shown in the above figure?
(ii) If a real inverted image is to be formed by this lens at a distance of 7m from the pole, then show with calculation where should the object be placed?
(iii) Draw a neatly labelled diagram of the image formation mentioned in (ii)
OR
A 10 cm long pencil is placed 5 cm in front of a concave mirror having a radius of curvature of 40 cm. [2 + 1 + 2]
(i) Determine the position of the image formed by this mirror.
(ii) What is the size of the image?
(iii) Draw a ray diagram to show the formation of the image as mentioned in the part (i).
Solution:
(i) Convex Lens
(ii) Given, υ = 7 m, f = 5 m
We know that, \(\frac{1}{f}=\frac{1}{υ}-\frac{1}{u}\)
Putting the values in the equation, we get,
\(\frac{1}{5}=\frac{1}{7}-\frac{1}{u}\)
\(\frac{1}{u}=\frac{1}{7}-\frac{1}{5}=\frac{5-7}{35}=\frac{-2}{35}\)
u = – \(\frac{35}{2}\) = -17.5 m
Hence, the object will be placed 17.5 m on the left of the convex lens.
Section – E
Question No. 37 to 39 are case-based/data -based questions with 2 to 3 short sub-parts.
Internal choice is provided in one of these sub-parts.
Question 37.
The table given below shows the hints given by the quiz master in a quiz. [4]
S.No | HINT |
(i) | Substance ‘C’ is used as a preservative. |
(ii) | ‘C’ has two carbon atoms; ‘C’ is obtained by the reaction of ‘C’ in presence of alkaline Potassium permanganate followed by acidification. |
(iii) | Misuse of A’ in industries is prevented by adding Methanol, Benzene, and pyridine to ‘A’. |
(iv) | ‘F’ is formed on heating ‘A’ in presence of cone Sulphuric acid. |
(v) | ‘F’ reacts with Hydrogen gas in presence of Nickel and Palladium catalyst. |
Based on the above hints answer the following questions
(a) Give the IUPAC names of A and F
(b) Illustrate with the help of chemical equations the changes taking place. (A → C and A → F)
OR
Name the chemical reactions which occur in steps 2 and 5. Identify the compounds formed in these steps if A’ is replaced with its next homologue.
Solution:
(a) IUPAC name of A – Ethanol
IUPAC name of F – Ethene
OR
When ethanol is heated in the presence of alkaline Potassium permanganate followed by acidification in step 2, ethanoic acid is obtained. In this reaction, alkaline KMnO4 acts as an oxidising agent as it oxides ethanol to ethanoic acid. Therefore, it is an example of oxidation chemical reaction.
When unsaturated compound, ethene (F) reacts with Hydrogen gas in presence of Nickel and Palladium catalyst in step 5, a saturated compound ethane is formed. This is an example of Hydrogenation chemical reaction which is an addition reaction where hydrogen molecules are used to saturate organic compounds
If A; is replaced with its next homologue, i.e., propanol, than the compound formed will be propanoic acid and propene.
Question 38.
Figures (a) to (d) given below represent the type of ear lobes present in a family consisting of 2 children – Rahul, Nisha and their parents. [4]
Excited by his observation of different types of ear lobes present in his family, Rahul conducted a survey of the type of ear lobes found {Figure (e) and (f)} in his classmates. He found two types of ear lobes in his classmates as per the frequency given below:
Sex | Free | Attached |
Male | 36 | 14 |
Female | 31 | 19 |
On the basis of above data answer the following questions.
(a) Which of the two characteristics – ‘free ear lobe’ or ‘attached ear lobe’ appears to be dominant in this case? Why?
(b) Is the inheritance of the free ear lobe linked with sex of the individual? Give reason for your answer.
(c) What type of ear lobe is present in father, mother, Rahul and his sister Nisha? Write the genetic constitution of each of these family members which explains the inheritance of this character in this family?
(Gene for Free ear lobe is represented by F and gene for attached ear lobe is represented by f for writing the genetic constitution).
OR
Suresh’s parents have attached earl obes. What type of ear lobe can be seen in Suresh and his sister , ‘ Siya? Explain by giving the genetic composition of all.
Solution:
(a) Free ear lobe is dominant because it is found in a large majority of the population.
(b) No, it is not sex linked. As per the data of the family as well as the class, it is indicated that free ear lobe is present in males as well as in females.
(c) Father – Ff (free ear lobe), Mother – Ff (free ear lobe), Rahul – ff (attached ear lobe) and Nisha – Ff (free ear lobe).
OR
Both Suresh’s father and mother have attached ear lobes (ff). If both parents have recessive character, then all the children will have recessive character only. Therefore, Suresh and her sister siya will also have attached ear lobe (ff).
Suresh’s Father ff (attached ear lobe),
Suresh’s Mother ff (attached ear lobe),
Suresh – ff (attached ear lobe),
Siya – ff (attached ear lobe).
Question 39.
Vinita and Ahmed demonstrated a circuit that operates the two headlights and the two sidelights of a car, in their school exhibition. Based on their demonstrated circuit, answer the following questions.
(i) State what happens when switch A is connected to
(a) Position 2 (b) Position 3
(ii) Find the potential difference across each lamp when lit.
(iii) Calculate the current
(a) in each 12 Ω lamp when lit.
(b) In each 4 Ω lamp when lit.
OR
(iv) Show, with calculations, which type of lamp, 4.0 Ω or 12 Ω, has the higher power.
Solution:
(i) (a) Both the 12 Ω lamps (only) ON.
(b) Both the 4 Ω lamps (only) ON.
(ii) 12 V for both sets of lamps and all of them are in parallel.
(iii) 12 Ω lamps are ON when the wire is connected to position 2.
Voltage across both 4 Ω lamps = 12 V.
Net resistance = R = \(\frac{12 \times 12}{12+12}\) = 6 Ω
V = IR (Ohm’s law).
Total current I = \(\frac{V}{R}=\frac{12}{6}\) = 2A
As both resistance connected in penallel, current is equally divided in each resistance.
Hence, the current in each 12 Q lamp when lit is I Ampere.
(b) 4 Ω lamps are ON when the wire is connected to position 3.
Voltage across both 4 Ω lamps = 12 V.
Net resistance R’ = \(\frac{4 \times 4}{4+4}\) = 2 Ω
V = IR’ (Ohm’s law). I = \(\frac{\mathrm{V}}{\mathrm{R}^{\prime}}=\frac{12}{2}\) = 6A
Current is equally distributed in each resistance
Hence, the current in each 4 Ω lamp when lit is \(\frac{6}{2}\) i.e., 3 Ampere.
OR
(iv) All lamps are in parallel and hence same V for all lamps.
We know that,
P= \(\frac{V^2}{R}\)
For 4 Ω lamps → P = \(\frac{\mathrm{V}^2}{\mathrm{R}}=\frac{12 \times 12}{4}\) = 36 W
For 12 Ω lamps → P = \(\frac{\mathrm{V}^2}{\mathrm{R}}=\frac{12 \times 12}{12}\) = 12W
Hence 4 Ω lamps will have higher power.