CBSE Sample Papers for Class 10 Science Paper 4
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 4.
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.
SECTION-A
Question 1.
In a bisexual flower inspite of the young stamens being removed artificially, the flower produces fruit. How is it possible?
Question 2.
Which part of root is involved in the exchange of respiratory gases in plants?
Question 3.
Elements have been arranged in the following sequence on the basis of their increasing atomic masses.
F, Na, Mg, Al, Si, P, S, CI, Ar, K
- Pick two sets of elements which have similar properties.
- The given sequence represents which law of classification of elements?
Question 4.
An object is placed at a distance of 30 cm from a concave lens of focal length 15 cm. List four characteristics (Nature, position, etc.) of the image formed by the lens.
Question 5.
Describe how hydro-energy can be converted into electrical energy. Write
any two limitations of hydro-energy.
Question 6.
Identify the oxidising agent (oxidant) in the following reactions.
- Pb3O4 + 8HCl — 3PbCl2 + Cl2 + 4H20
- 2Mg + O2 = 2MgO
- CuSO4 + Zn – Cu + ZnSO4
- V2O5 + 5Ca – 2V + 5Cao
- 3Fe + 4H2O — Fe3O4 + 4H2
- CuO + H2 – Cu + H2O
Question 7.
Crystals of copper sulphate are heated in a test tube for some time.
- What is the colour of copper sulphate crystals
- before heating, and
- after heating?
- Which one of these has a higher concentration of H+ ions?
I M HCl or IM CH3COOH
Question 8.
Identify the elements with the following property and arrange them in
increasing order of their reactivity.
- An element which is a soft and reactive metal.
- The metal which is an important constituent of limestone.
- The metal which exists in liquid state at room temperature.
OR
The following table shows the position of six elements A, B, C, D, E and F in the Periodic Table.
Groups —> Periods —^ | 1 | 2 | 3 to 12 | 13 | 14 | 15 | 16 | 17 | 18 |
2. | A | B | C | ||||||
3. | D | E | F |
Using the above table answer the following questions:
- Which element will form only covalent compounds?
- Which element is a metal with valency 2?
- Which element is a non-metal with valency 3?
- Write a common name for the family of elements C and F.
- Out of D and E, which one has a bigger atomic radius and why?
Question 9.
What are the adaptations of leaf for photosynthesis?
Question 10.
What is vegetative propagation? State two advantages and two disadvantages of this method.
Question 11.
Distinguish between the acquired traits and the inherited traits in tabular form, giving one example for each.
OR
Explain with the help of an example each, how the following provide evidences in favour of evolution:
- Homologous organs
- Analogous organs
- Fossils
Question 12.
In a quarry of sandstone, a digger found some bones below the rocks. He took them out and was about to throw them away when his fellow digger told him that this could be a fossil and they should hand it over to the museum. Answer the following questions based on the above situation:
- Which values are promoted by the fellow digger?
- What contributions are the diggers making to the scientific world?
- Imagine yourself to be the person in the museum whom the diggers approach. What would be your response to the diggers’ discovery?
Question 13.
An object 4 cm in height, is placed at 15 cm in front of a concave mirror of focal length 10 cm. At what distance from the mirror should a screen be placed to obtain a sharp image of the object. Calculate the height of the image.
OR
At what distance from a concave lens of focal length 20 cm a 6 cm tall object be placed so as to obtain its image at 15 cm from the lens? Also calculate the size of the image formed. Draw a ray diagram to justify your answer for the above situation and label it.
Question 14.
- Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.
- Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of 1.5 V, 5 12, 10 12 and 15 12 resistors and a plug key, all connected in series.
Question 15.
- Explain an activity to show that a current-carrying conductor experiences a force when placed in a magnetic field.
- State the rule which gives the direction of force acting on the conductor.
Question 16.
- Giving one example of each, explain how the following metals are obtained from their compounds by the process of reduction.
- Metal ‘A’ which is low in the activity series of metals.
- Metal ‘B’ which is in the middle of the activity series of metals.
- Metal ‘C’ which is high in the activity series of metals.
- What is meant by refining of metals? In the electrolytic refining of metal M, name the cathode, anode and the electrolyte.
Question 17.
An organic compound A having molecular formula C2H4 O2 racts with sodium metal and evolves a gas B which readily catches fire. A also reacts with ethanol in the presence of conc H2SO4 to form sweet smelling substance C used in making perfumes.
- Identify the compounds A, B and C and write their names.
- Write balanced chemical equations to represent conversion of
- compound A into compound B
- compound A into compound C
- Write the chemical composition of detergents. Mention their advantage over soaps for washing clothes.
OR
- What are hydrocarbons? Give one example.
- Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
- What is a functional group? Give examples of two different functional groups.
Question 18.
How are involuntary actions and reflex actions different from each other?
Question 19.
With the help of an activity show the blue colour of the sky and the reddish appearance of the sun at the sunrise or sunset.
Question 20.
Explain the underlying principle and working of direct current generator (or DC dynamo) by drawing a labelled diagram.
Question 21.
- State two advantages of conserving
- forests, and
- wildlife.
- Explain two main advantages associated with water harvesting at the community level.
- In the following food chain, 100 J of energy is available to the lion. How much energy was available to the producer?
Plants → Deer → Lion
OR
- Write the full name of the group of compounds mainly responsible for the depletion of ozone layer.
- Prepare a list of five activities that you perform daily in which natural resources can be conserved or energy utilization can be minimized.
OR
SECTION-B
Question 22.
During an experiment, Amit observed that blue colour of aqueous copper sulphate solution changed to pale green by immersing a metallic rod for some time.
- Which metallic rod Amit might have immersed in the solution and what colour would be observed on the rod?
- Mention the type of reaction in this case.
Question 23.
A student adds a spoonfull of powdered sodium hydrogencarbonate to a flask containing ethanoic acid. List two main observations, he must note in his notebook, about the reaction that takes place. Also, write chemical equation for the reaction.
Question 24.
A student sets up the apparatus for the experiment to show that CO2 is released during respiration. After 2 hours, what would he observe?
Question 25.
Draw a labelled diagram to show that particular stage of binary fission in Amoeba in which its nucleus elongates and divide into two and a constriction appears in its cell membrane.
Question 26.
In the given figure, a narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism it produces a spectrum on a screen.
Which two positions correspond closely to the colour of
- egg yolk,
- ladyfinger?
Question 27.
In an experiment to find the equivalent resistance 0 of a series combination of two resistors R1 and R2, a student uses the circuit shown here. Will ham the circuit give the correct reading for current I and voltage V? Justify your answer.
OR
The given circuit diagram shows the experimental arrangement of different circuit components for determination of equivalent resistance of two resistors connected in series. Identify the components X, Y and Z shown in the circuit respectively.
Answers
SECTION-A
Answers 1.
This is because the pistil is intact due to which cross-pollination takes place
leading to fertilisation and formation of fruit.
Answers 2.
Root hairs are involved in the exchange of respiratory gases in plants.
Answers 3.
-
- F and CI
- Na and K
- Newlands’ Law of Octaves
Answers 4.
• Virtual
• Erect
• Diminished
• On the same side as the object
Answers 5.
The water from the high level in the dam is carried through pipes to the turbine, at the bottom of the dam. Moving turbine rotates the coils of the dynamo to produce electricity. Two limitations of hydro-energy:
- Flowing water is not available at all places.
- Kinetic energy of flowing water can rotate a wheel or turn a turbine to produce electricity only when the water is available in sufficient quantity.
Answers 6.
- Pb3O4
- O2
- CuSO4
- V2O5
- H20
- CuO
Answers 7.
-
- Blue
- White
- 1 M HCI
Answers 8.
- Na or K .
- Ca
- Hg
Reactivity order: Hg < Ca < Na < K
OR
- E
- D
- B.
- The noble gases.
- D has bigger atomic radius. The atomic radius decreases in moving from left to right along a period. This is due to an increase in nuclear charge which tends to pull the electrons closer to the nucleus and reduces the size of the atom.
Answers 9.
- Leaves provide large surface area for maximum light absorption.
- Leaves are arranged at right angles to the light source in a way that causes overlapping.
- The extensive network of veins enables quick transport of substances to and from the mesophyll cells.
- Presence of numerous stomata for gaseous exchange.
- The chloroplasts are more in number on the upper surface of leaves.
Answers 10.
Vegetative propagation is a process in which any vegetative part of a plant
(root, stem or leaf) gives rise to a new plant under appropriate conditions.
Two advantages:
- Large number of plants obtained in a short interval.
- Propagation of seedless plants is made possible.
Two disadvantages:
- No genetic variations, so, less adaptability to the environment.
- The disease of plants gets transferred to the offsprings.
Question 11.
S.No. | Acquired Traits | Inherited Traits |
1. | Develop during one’s life time. | Are inherited from the parents. |
2. | Do not bring about changes in the DNA of the germ cells. | Result due to existing changes in the DNA of the germ cells. |
3. | Cannot be passed on to the progeny. | Can be passed on to the progeny. |
4. | Examples: Acquired knowledge, loss of weight. | Examples: Skin colour, colour of the eye |
OR
- Homologous Organs : The study of these organs suggests that these organisms with organs having same structure but performing different functions have evolved from a common ancestor, e.g. forelimbs of different vertebrates.
- Analogous Organs : The study of these apparently similar organs suggests that the organisms with apparently similar organs do not share common ancestory. Similarity in these organs is superficial, design and the structure of these organs are very different, e.g. wings of bird and wings of butterfly.
- Fossils : They provide the missing link between the species, e.g. fossils of dinosaurs with feathers, fossils of prehistoric horse.
Answers 12.
- Rational thinking, awareness, preservation of heritage.
- They provided a link which can help scientists to study the process of evolution and know more about the world in which humans did not exist.
- I would take the bones’ samples and send them for carbon dating to find which period they belong to.
Answers 13.
h1 = + 4 cm, f = – 10 cm, u = – 15 cm, v = ?, h2 = ?
Answers 14.
(i) Here, I = 10 A, V = 220 V
By Ohm’s law,
Answers 15.
- A small aluminium rod suspended horizontally from a stand using two connecting wires. Place a strong umu horseshoe magnet in such a way that the rod lies between the two poles with the magnetic field directed upwards. For this, put the north pole of the magnet vertically below and south pole vertically above the aluminium rod. Connect the HAO aluminium rod in series with a battery, a key and a rheostat. Pass a current through the aluminium rod from one end to other (B to A ). The rod is displaced towards left. When the direction of current flowing through the rod is reversed, the
displacement of rod across towards right.
- Fleming’s left-hand rule. Stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular to one another. If the forefinger points in the direction of magnetic field and the middle finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor.
Answers 16.
- • By heating
Example : HgS + O2 \(\underrightarrow { Heat }\) Hg + SO2
• By reduction of its oxide with carbon/carbon monoxide
Example : ZnO + C → Zn + CO
• By electrolysis of fused compounds of the metal
Example : - Refining is the method of removing impurities from the crude metal.
Cathode: Pure M
Anode: Impure (crude) M
Electrolyte: A water soluble salt of M
Answers 17.
- A is CH3COOH (ethanoic acid)
B is H2 (Hydrogen gas)
C is CH3COOC2H5 (Ethyl ethanoate) - • 2CH3COOH + 2Na \(\underrightarrow { Conc\quad H_{ 2 }SO_{ 4 } }\) , 2CH3COONa + H2
• CH3COOH + C2 H5 OH \(\underrightarrow { Conc\quad H_{ 2 }SO_{ 4 } }\) , CH3COOC2H5 + H2O - Chemically, detergents are ammonium or sulphonate salts of long chain carboxylic acid. Detergents can be effectively used in hard water whereas soaps cannot be used.
OR
- Compounds of carbon and hydrogen are called hydrocarbons. e.g. methane, ethane, etc.
- Saturated hydrocarbons contain carbon-carbon single bonds, e.g., methane, ethane. Unsaturated hydrocarbons contain atleast one carbon carbon double or triple bond, e.g., ethene, ethyne.
- Functional group is an atom or group of atoms joined in a specific manner which is responsible for the characteristics properties of the organic compounds, e.g., OH, -CHO.
Question 18.
S.No. | Involuntary actions | Reflex actions |
1. | They involve autonomic nervous system. | They involve all parts of voluntary nervous system. |
2. | They usually occur in response to internal stimuli. | They operate against harmful stimuli which are generally external and may cause injury. |
3. | They are connected with functioning of internal body parts. | They are connected with emergency. |
4. | These are regulated by medulla (hindbrain). | Reflex action is controlled by spinal cord. |
5. | The speed of response is slower. | The speed of response is very fast. |
6. | Example: Beating of heart muscle. | Example: Removal of hand with jerk when someone touches a hot object accidently. |
Answers 19.
Activity:
- Place a source of light S such as an electric bulb at the focus of a converging lens Lj. This lens provides a parallel beam of light.
- Allow the light beam to pass through a transparent glass beaker B of capacity 500 mL.
- After passing through the beaker containing about 400 mL of water allow the light beam to pass through a circular hole made in cardboard C. Obtain a sharp image of the hole on a screen MN using another convex lens L2.
- Dissolve about 200 g of sodium thiosulphate (hypo) in water taken in the beaker B. Add about 1 to 2 mL of concentrated sulphuric acid with the help of an injection syringe dropwise in the beaker containing hypo solution.
- What do you observe? You will notice fine microscopic sulphur particles precipitating in about 2 to 3 seconds. As the sulphur particles begin to form, you can observe the blue light from the sides of the beaker. This is due to scattering of short wavelengths by minute colloidal sulphur particles. Observe the colour of the light patch on the screen. It is interesting to observe the change in colour of the patch-from orange red colour in the beginning to bright crimson red colour later on the screen.
This activity demonstrates the scattering phenomena of light that helps us to understand the bluish colour of the sky in general and the reddish appearance of the sun at the sunrise or the sunset.
Answers 20.
A device used to convert mechanical energy into electrical energy is called
an electric generator. An armature-coil rotating in a magnetic field develops an alternating emf and sends alternating current in an external circuit. If, however, the connections of the ends of the coil to the external circuit are interchanged every time the emf in the coil reverses, the current in the external circuit flows always in the same direction. This is the principle of a DC dynamo.
The working of a single-coil DC dvnamo is shown in the figure. The ends of the armature-coil ABCD are connected to the two separated segments Ry of a single copper ring R, which is called the ‘split-ring commutator’. R, and R, rotate along with the armature between two brushes B, and B, to which the external circuit is connected.
When the armature-coil ABCD is rotated clockwise (say), an emf is induced in the coil and a current flows in the direction ABCD (Fleming’s right-hand rule), as shown in Fig (a). In the external circuit, the current flows from B to B2. For half the revolution, R, is in contact with B, and R, with B2. But as soon as the coil passes the vertical, R, comes in contact with B, and R, with B, and remain so during the next half revolution Fig. (b). Although the induced emf in the coil is reversed and the current in the coil flows in the direction DCBA, but in the external circuit the current still flows from B, to B2
The current generated by such a simple dynamo is uni-directional. As long as the coil is rotating, the direct current flows through the device connected
to the terminals of the generator.
Answers 21.
- Conserving forests helps in
- retaining subsoil water and
- checking floods. Conserving wildlife helps in
- maintaining ecological balance and
- protecting the nature.
- Water stored during rainy season can be used as and when required by the community.
- Ground water level increases due to recharging.
- Plants are able to capture only 1% of the energy of sunlight. 10% of energy is present at each step and reaches the next level of consumers. So, if 100 J of energy is available to the lion, then the energy available to the producer is 10,00,000 J.
OR
- Chlorofluorocarbons
- Unused water in the water bottle may be used for watering plants.
- Close all the taps before you go to sleep.
- Avoid using a hose pipe for watering plants and instead use a mug.
- Wash vehicles only when they are dirty.
- Use fan and light only when required.
- Use solar water heating devices.
- Use CFL in place of conventional bulbs/tubes. (Any five)
SECTION-B
Answers 22.
- Amit immersed iron rod in the solution. Reddish brown colour of copper would be observed on the rod.
- Displacement reaction.
Answers 23.
The two main observations are :
- Brisk effervescence
- Evolution of colourless and odourless gas
CH3COOH + NaHCO3 – CH3COONa + H2O + CO2
Answers 24.
He would observe the rise in water level in the beaker. This is because vacuum is created due to absorption of CO, by KOH which raises the water level.
Answers 25.
Answers 26.
- Colour position that corresponds to egg yolk = 5 (yellow)
- Colour position that corresponds to ladyfinger = 4 (green)
Answers 27.
The circuit will give correct reading for current I but incorrect reading for voltage V. The voltmeter has to be put in parallel with the resistances being measured and not across the ammeter.
OR
X represents the ammeter as it is connected in series.
Y represents the voltmeter as it is connected in parallel.
Z represents the rheostat (variable resistance)
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