CBSE Sample Papers for Class 10 Science Paper 2
These Sample papers are part of CBSE Sample Papers for Class 10 Science. Here we have given CBSE Sample Papers for Class 10 Science Paper 2.
Time Allowed: 3 hours
Max. Marks: 80
General Instructions:
- The question paper comprises two sections, A and B. You are to attempt both the sections.
- All questions are compulsory.
- All questions of Section-A and B are to be attempted separately.
- There is an internal choice in three questions of three marks each, two questions of five marks each and one question
- (for assessing the practical skills) of two marks.
- Question numbers 1 and 2 in Section-A are one mark question. They are to be answered in one word or in one sentence.
- Question numbers 3 to 5 in Section- A are two marks questions. These are to be answered in 30 words each.
- Question numbers 6 to 15 in Section-A are three marks questions. These are to be answered in about 50 words each.
- Question numbers 16 to 21 in Section-d are five marks questions. These are to be answered in 70 words each.
- Question numbers 22 to 27 in Section- B are based on practical skills. Each question is a two marks question. These are to be answered in brief.
SECTIONS – A
Question 1.
What will happen to a plant if its xylem is removed?
Question 2.
Colonies of yeast fail to multiply in water, but multiple in sugar solution. Give one reason.
Question 3.
- Which two criteria did Mendeleev use to classify the elements in his periodic table?
- State Mendeleev’s periodic law.
Question 4.
- Explain why a ray of light passing through the centre of curvature of a concave mirror gets reflected along the same path.
- Draw the given diagram in your answer-book and complete it for the path of ray of light beyond the lens.<
Question 5.
What is the main constituent of biogas? How is biogas obtained from biomass? Write any two advantages of using this gas.
Question 6.
An apparatus was set-up as shown in the figure. It was observed that when an aqueous solution of HCl was taken in the beaker and the circuit was closed, the bulb in the circuit began to glow, but it did not glow when the experiment was repeated with glucose solution. What could be the reason? Would the bulb glow if the same experiment is repeated with an aqueous solution of
- NaOH
- NaCl? Why?
Question 7.
2 g of ferrous sulphate crystals were heated in a hard glass test tube and observations recorded.
- What was the successive colour change?
- Identify the liquid droplets collected on the cooler parts of the test tube.
- What type of odour is observed on heating ferrous sulphate crystals?
- Name the products obtained on heating ferrous sulphate crystals.
- What type of reaction is taking place?
Question 8.
- Why could no fixed position be given to hvdrogen in Mendeleev’s periodic table?
- How and whv does the atomic size varv as vou go:
- from left to right along a period?
- down a group?
OR
- Why did Mendeleev have gaps in his periodic table?
- How does electronic configurations of atoms change in a period with increase in atomic number?
Question 9.
Draw a diagram of human alimentary canal and label on it:
Oesophagus, Gall bladder. Liver and Pancreas.
OR
Draw a diagram of excretory svstem in human beings and label on it:
Aorta, vena cava, urinary bladder, urethra.
Question 10.
- Explain the terms:
- implantation
- placenta
- W’hat is the average duration of human pregnancv?
Question 11.
Explain analogous organs and homologous organs. Identifv the analogous and homologous organs amongst the following:
Wings of an insect, wings of a bat, forelimbs of frog, forelimbs of a human.
Question 12.
Distinguish between inherited traits and acquired traits giving one example of each. Give reason why the traits acquired by an individual during the life time are not inherited.
Question 13.
An object is placed perpendicular to the principal axis of a convex lens of focal length 8 cm. The distance of the object from the lens is 12 cm. Eind the position and nature of the image.
OR
Define the term magnification as referred to spherical mirrors. If a concave mirror forms a real image 40 cm from the mirror, when the object is placed at a distance of 20 cm from its pole, find the focal length of the mirror.
Question 14.
Mr. Sharma, a propertv dealer, had many expensive appliances at his home like refrigerator, air conditioners, geyser, etc. but he forgot to put earth wire connections to these appliances. One day his vounger daughter opened the fridge and suffered a severe electric shock though, she was saved.
Answer the following questions based on the situation given above.
- Why did it happen?
- How can one save himself/herself from electric shocks by these electrical appliances?
- What values are being neglected by Mr. Sharma?
Question 15.
Two resistors, with resistances 5Ω. and 10Ω respectively are to be connected to a battery of emf 6v so as to obtain:
- minimum current flowing
- maximum current flowing
- How will you connect the resistances in each case?
- Calculate the strength of the total current in the circuit in the two cases.
Question 16.
Account for the following:
- Melting and boiling points of ionic compounds are high.
- Aluminium is more active than iron, yet there is less corrosion of aluminium when both are exposed to air.
- Solder is used for welding electrical wires together.
- A sulphide ore is converted into its oxide to extract the metal.
- Tarnished copper vessels are cleaned with tamarind juice.
Question 17.
- Write a chemical equation of each of the following types of chemical reactions of organic compounds.
- Oxidation reaction
- Addition reaction
- Substitution reaction
- What is ethanol? What happens when it is heated with excess cone. H2SO4 at 443 K? Write the role of cone. H2SO4 in this reaction.
Question 18.
- Name the plant growth hormone which is synthesized at the shoot tip. Explain briefly why does a plant shoot bend towards light during its growth.
- With the help of a schematic diagram, trace the sequence of events occurring, when voit step on a sharp object. Name this action.
OR
- Compare and contrast nervous and hormonal mechanism for control and coordination in animals.
- Draw a diagram of the human brain.
- Label on it cerebrum, cerebellum.
- Wrhat is the role of cerebellum?
Question 19.
- What is a magnetic field? How can the direction of magnetic field lines at a place be determined?
- State the rule for the direction of the magnetic field produced around a current carrying conductor. Draw a sketch of the pattern of field lines due to a current flowing through a straight conductor.
OR
- What is a solenoid? Draw a sketch of the pattern of field lines of the magnetic field through and around a current carrying solenoid.
- Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of the magnetic field inside and outside the loop.
Question 20.
A person is unable to see distinctly the words printed on a newspaper. Name the defect of vision he is suffering from. Draw ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.
Question 21.
- What is sustainable development? Why is it necessary?
- What is water harvesting? List its four benefits.
SECTION-B
Question 22.
The pH values of four solution A, B C, and D as determined by a student are 3, 7, 12 and 8 respectively.
- Identify the most acidic and most basic solutions.
- Arrange the above four solutions in the decreasing order of their hydrogen ion concentration.
Question 23.
What do you observe when you add sodium bicarbonate to acetic acid? How would you identify the gas released in the reaction? Describe briefly.
Question 24.
While doing the experiment to show light is necessary for photosynthesis, the student was given following suggestions by his fellow students. Which are the correct suggestions given by his fellow students?
- Safranine should be used instead of iodine.
- The leaf should be boiled in alcohol with water bath to remove chlorophyll.
- Transparent paper strip should be used instead of black paper strip.
- The plant should be destarched before starting the experiment.
Question 25.
Draw a diagram showing different parts of an embryo of gram seed and label them.
Question 26.
In the experiment ‘To trace the path of ray of light passing through a glass prism’.
1. What is the correct set-up?
2. Justify for your correct set-up?
Question 27.
When a (60W, 220V) bulb and a (100 W, 220 V) bulb are connected in series, then which bulb will glow brighter?
OR
In a voltmeter there are 20 divisions between the O mark and 0.5 V mark. Calculate the least count of the voltmeter.
SECTION-A
Answer 1.
The xylem tissue transports water and minerals from the soil to the leaves of a plant for photosynthesis. If xvlem is removed, upward movement of water will stop leading to wilting of leaves and ultimately causes death of a plant.
Answer 2.
Sugar provides energy for sustaining all life activities in yeasts. In water, it fails to reproduce because of inadequate energy in its cells.
Answer 3.
- The two criteria used by Mendeleev to classify the elements in his periodic table are
- Increasing order of atomic masses.
- Similarity in the chemical properties of elements.
- Mendeleev’s periodic law : The properties of elements are the periodic function of their atomic masses.
Answer 4.
- Because the angle of incidence is 0° or Ray passing through the centre of curvature is incident normally to the mirror.
Answer 5.
- Methane (CH4)
- By anaerobic decomposition of biomass in the presence of micro-organisms.
- It is a clean fuel
It burns without smoke
It leaves no residue
Its heat capacity/calorific value is high
Safe and efficient’(Any two)
Answer 6.
The bulb could glow when an aqueous solution of HCl was taken because HCl (aq) provided hydrogen and chloride (H+ and Cl”) ions which are carriers of electric charges in a solution, while glucose (being a covalent compound) did not furnish any ions in the solution.
- NaOH : The bulb will glow
- NaCl : The bulb will glow
Because both of them being ionic compounds furnish ions in aqueous solutions.
Answer 7.
- Green to white, then brown
- Water
- As of burning sulphur
- Ferric oxide, sulphur dioxide, sulphur trioxide
- Decomposition reaction
Answer 8.
- The properties of hydrogen resemble with both alkali metals as well as halogens. So, on the basis of its properties it could be placed in group 1 (with alkali metals) as well as in group VII (with halogens).
- Atomic size decreases from left to right along a period because of increase in nuclear charge (atomic number) which tends to pull the electrons closer to the nucleus.
- Atomic size increases down the group due to addition of new shells (orbits).
OR
- Mendeleev left some gaps in his periodic table for the elements that were not known at his time. These gaps were left for the elements which could match with other elements of that group but had not discovered by that time.
- On moving from left to right along a period one electron each is added successively to the same whence shell of atom. From left to right, whence electrons increase from 1 to 8 (1 to 2 in first period).
Answer 9.
Answer 10.
-
- Implantation: Implantation is the process of attachment of the developing embryo or the fertilized egg with the uterine wall.
- Placenta: A disc-shaped special tissue develops between the wall of the uterus and the embryo for exchange of nutrients, supply of oxygen and excretion of waste products.
- The average duration of human pregnancy is 280 days or 40 weeks or 9 months.
Answer 11.
Analogous organs: Those organs which have different basic structural designs and origin, but perform similar functions are called analogous organs.
Homologous organs : Those organs which have the same basic structural design and origin, but perform different functions are called homologous organs.
Analogous organs from the given list : Wings of an insect, wings of a bat.
Homologous organs from the given list : Forelimbs of a frog, forelimbs of a human.
Answer 12.
Inherited Traits | Acquired Traits |
Changes or characters in the reproductive tissues only can be passed on to the DNA of the germ cells/next generation. | Changes in non-reproductive tissues cannot be passed on to the DNA of the germ cells/next generation. |
Example: Tails of mice/skin colour. | Example: Life time experiences/ tanning of skin when exposed to sun. |
Reason : Change in non-reproductive tissues cannot be passed on to the DNA of the germ cells.
Answer 13.
u = – 12 cm, ƒ = +8 cm, u = ?
\(\frac { 1 }{ u } -\frac { 1 }{ u } =\frac { 1 }{ f }\)
\(\frac { 1 }{ u } -\frac { 1 }{ (-12) } =\frac { 1 }{ 8 }\)
u = + 24 cm
The image is real and inverted.
The relative extent to which the image of an object is magnified with respect to object size. It is the ratio of size of the image to the size of the object. v = – 40 cm, u = -20 cm, ƒ = ?
\(\frac { 1 }{ f } =\frac { 1 }{ u } +\frac { 1 }{ u }\)
\(\frac { 1 }{ f } =\frac { 1 }{ -10 } +\frac { 1 }{ -20 }\)
ƒ = \(\frac { -40 }{ 3 }\) cm
Answer 14.
- This happened because earth wire was not used in the electric appliances. The purpose of earthing is that in c£se of an insulation failure in some appliance, this wire connected to the metal body will provide a path for the current to flow in the ground.
- By providing proper earthing in all electrical appliances, connecting electric fuse in circuits, never touch an electric switch or appliance with wet hands.
- Carefulness and vigilance while handling electric gadgets.
Answer 15.
-
- For obtaining minimum current, the two resistors should be connected in series.
- For obtaining maximum current the two resistors should be connected in parallel.
- Given, R1 = 5Ω, R2= 10Ω and V = 6 V
For parallel arrangement, the equivalent resistance is given by 11.1
Answer 16.
- Large amount of heat energy is required to break the inter-ionic attractive forces.
- A thin but strong layer of aluminium oxide is formed on its surface which protects aluminium atoms underneath.
- Solder has a low melting point.
- It is easier to extract a metal from its oxide by the process of reduction than from its sulphide.
- Tamarind juice is acidic and neutralizes the basic layer of copper carbonate on tarnished copper vessels.
Answer 17.
1.
2.
• Ethanol is an alcohol having two carbon atoms in its molecule (C,HOH).
• Ethene is formed when it is heated with conc. H2SO4 at 443 K.
• Conc. H2SO4 acts as a dehydrating agent.
Answer 18.
1. Auxins is the harmone which is synthesised at the shoot tip of a plant. When the growing shoot of a plant detects light, auxin is synthesised at the shoot tip and diffuses towards the shady side of the shoot. This stimulates cells to grow longer on the shadier side causing the plant to bend.
2.
OR
1.
Nervous control | Hormonal control |
1. Information is passed as electrochemical conduction. | 1. Information is sent as a chemical substance through the blood stream. |
2. Information travels rapidly; in milliseconds. | 2. Information travels slowly. |
3. Response is immediate. | 3. Response is usually slow. |
4. Its effects are short-lived. | 4. Its effects are generally more prolonged. |
2. (a) and (b)
(c) Cerebellum balances the body and coordinates the muscular activity.
Answer 19.
- The region around a magnet in which magnetic force can be experienced is called a magnetic field. The direction of I Battery magnetic field lines at a point can be determined Plastic board by placing a magnetic compass at that point.
- Right hand thumb rule: Rh If you are holding a current carrying conductor in your right hand such that the thumb points in the direction of current then the direction of your wrapped fingers will give the direction of field lines of the magnetic field.
OR
1.
-
- A solenoid is a long coil containing a large number of close circular turns of insulated copper wire in the form of a cylinder.
- The magnetic field produced is similar to that produced by a bar magnet. Pattern of magnetic field lines due to a current carrying solenoid:
- Since the current passes through the loop is clockwise, therefore, the front face of the loop will be the south pole and the back face, i.e., the face touching the table will be north pole. According to right-hand rule, the direction of magnetic field inside the loop will be pointing downward. In outside the loop, the direction of magnetic field will be upward.
Answer 20.
• The person is suffering from Hypermetropia.
• Defective eye
• Two possible causes can be:
(i) the focal length of the eye lens is too long
(ii) the eyeball has become too small.
• Correction of the defect using appropriate lens
Answer 21.
- Sustainable development: Development which meets the current basic human needs, while preserving the resources for the needs of future generation. It is necessary for environmental conservation.
- Water harvesting: It is a method to capture every trickle of water that falls on the land. Following are some benefits of water harvesting:
- Recharges wells/Ground water.
- Provides moisture for vegetation.
- It is not lost by evaporation.
- It does not provide a breeding place for mosquitoes.
- Prevents ground water from contamination due to human and animal wastes. (Any Four)
SECTION-B
Answer 22.
- Solution having pH 3, i.e., A is the most acidic. Solution having pH 12, i.e., C is the most acidic.
- pH in decreasing order of hydrogen ion concentration:
A < B < D < C.
Answer 23.
A colourless gas with brisk effervescence is evolved on addition of sodium bicarbonate to acetic acid. Lime water turns milky when this gas is passed through it, thus the evolved gas is carbon dioxide.
Answer 24.
Suggestions II and IV are correct. Suggestion I is wrong because safranine is used to stain plant cell not to test the presence of starch. Suggestion III is wrong because transparent paper strip is permeable to sunlight.
Answer 25.
Answer 26.
- IV set-up is the correct set-up.
- The zero of the protector should be in the direction of the normal.
Answer 27.
The resistance of the bulb is given by R = \(\frac { V^{ 2 } }{ P }\). So, the resistance of 60 W bulb is more than the resistance of 100 W bulb. When they are connected in series, the current through both bulbs is same. Hence 60 W bulb will be more brighter because
P = 12R.
OR
Range of voltmeter, VR = 0.5 V
Number of divisions in voltmeter, VN = 20
Least count of voltmeter = \(\frac { V_{ R } }{ V_{ N } } =\frac { 0.5 }{ 20 } =0.025V\)
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