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Grade X

Science Mock Test

Mock Test Science

General Instructions:

(i) The question paper comprises 5 Sections, A, B, C, D and E. You are to attempt both the sections.

(ii) All questions are compulsory.

(iii) Internal choices are given in section B, C, D and E.

(iv) Question numbers 1 & 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.

(v) Question numbers 3 to 5 in Section B are two-marks questions. These are to be answered in about 30 words each.

(vi) Question numbers 6 to 15 in Section C are three-marks questions. These are to be answered in about 50 words each.

(vii) Question numbers 16 to 21 in Section D are five-marks questions. These are to be answered in about 70 words each.

(viii) Question numbers 22 to 27 in Section E are questions based on practical skills. Each question is of 2 marks. These are to be answered in brief.

Section A Q1. Write the reaction that takes place when limestone is heated. 1 mark

Q2. What is the 10% energy law? 1 mark

Section B Q3. What happens when 2 marks

(a) silver nitrate solution is added to copper (b) aluminium foil is added to hydrochloric acid

Q4. The atomic number of helium is 2, but it is not placed in the second group. Explain why.

OR

What are detergents? What change has been made in detergents to make them easily bio-degradable? Explain the cleansing action of detergents. 2 marks

Q5. What are the advantages of using LPG as a source of energy? 2 marks

Section C Q6. Despite the child receiving a copy of the parental DNA, it does not resemble its

parents in all aspects. Why? 3 marks

Q7. (a) Define principle focus of a concave mirror. (b) A concave mirror of 10 m radius is to be used in a solar cooker. How far must the cooker be placed from the optical centre of the mirror for it to receive maximum solar energy? 3 marks

Q8. A metal X does not react with water at all. What steps should be followed in the extraction of X from its ore XS. 3 marks

Q9. Which functional group is present in ethanol? Draw the structure of ethanol. When a piece of sodium is added to ethanol, a gas is evolved which burns with a ‘pop’ sound. Name the gas and also write the balanced chemical equation for the reaction. How can ethene be obtained from ethanol?

OR

(a). Write down the chemical reaction that takes place in a soda acid fire extinguisher? (b). Write the name of the acid present in the following substances: i. Tamarind ii. Oranges (c). State some uses of bleaching powder. 3 marks

Q10. Answer the following questions. 3 marks

(a) Label the given figure appropriately in the place of the numbers. (b) Write one function of each labelled part.

Q11. (a)

Find the potential drop across resistor R3 in the given circuit. It is given that R1 = 9 Ω, R2 = 18 Ω and R3 = 6 Ω (b) Which uses more energy — a 250-W TV in one hour or a 1200-W toaster in 15 minutes? 3 marks

Q12. A plant with blue colour flower denoted by BB is cross-bred with a pea plant with white flower denoted by ww. (a) What is the expected colour of the flowers in their F1 progeny? (b) What will be the percentage of plants bearing white flower in F2 generation, when the flowers of F1 plants were selfed? (c) State the expected ratio of the genotype BB and Bw in the F2 progeny.

OR

Evolution is not always equated with progress. Explain. 3 marks

Q13. The near point of a person’s eyes is 2 m. What is the nature and power of the lens required to correct the eye defect? 3 marks

Q14. Explain the working of an AC generator with the help of a diagram. 3 marks

Q15. (a) Why is there a need to use coal and petroleum judiciously? (b) Write four disadvantages of using coal and petroleum.

OR

(a). Differentiate between an AC generator and a DC generator. (b). What are “brushes”? 3 marks

Section D Q16. Label the following reactions according to their types. Explain your answers.

(a)

(b)

(c)

(d)

(e)

OR

(a) Write the name and formula of the main ore of aluminium. (b) What is alumina? Which reducing agent is used for the reduction of alumina? (c) Why is alumina dissolved in cryolite? 3 marks

Q17. What facilitates transport of water to greater heights in plants during day time? Explain the process and write about its importance.

OR

(a). What is the difference between the movement of a leg on touching a hot object and the movement of a leg during walking? (b). Give a brief account of the response elicited in the leg on touching a hot 5 marks

object. (c). What is the role of the spinal cord and the brain in reflex arc?

Q18. (a) Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone. (b) Draw the diagram of human female reproductive system and label the parts where

(i) fertilisation takes place (ii) implantation of the fertilised egg occurs

(c) Explain how the embryo gets nourishment inside the mother's body. 5 marks

Q19. Both soap and detergent are some type of salts. What is the difference between them? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water ? List two problems that arise due to the use of detergents instead of soaps 5 marks

Q20. The refractive index of ethyl alcohol, carbon disulphide and water are 1.36, 1.63 and 1.33 respectively. In which medium will light travel the fastest? (Speed of light in air = 3 × 108 m/s) 5 marks

Q21. (a) How much work is done in moving a 4 C negative charge across a potential difference of 10 V? (b) Draw the diagram of a circuit that one may use for verifying Ohm’s law. (c) On what basis are materials classified as electrical conductors and electrical insulators?

OR

(a) What is Joule’s law of heating? (b) Name two devices that work on the principle of Joule’s heating. (c) An electrical device having a resistance of 10 Ω is connected to a 30 V source. Calculate the amount of heat generated by the device in 10 minutes. 5 marks

Section E Q22. Anuj places a potted plant in a dark room for three days. He then places the plant

on a glass plate along side a watch glass containing potassium hydroxide. He covers the plant with a bell jar and seals the bottom of the jar with vaseline. He then places the setup in sunlight for two hours. After two hours, he takes a leaf from the plant and performs iodine test to determine the presence of starch in the leaf. What possible observations will he make? Justify your answer.

OR

Three leaves (I, II, III) of a potted plant were covered with strips of black paper of different widths.

The plant was then exposed to sunlight for 6 hours. Write the sequence that represents the starch formation the given leaves in increasing order. Support your answer with proper explanation.

2 marks

Q23. Rohan has studied about displacement reactions in his class. His elder brother told him that while performing an experiment in chemistry laboratory, he obtained a purple-coloured solution on passing chlorine gas through potassium iodide solution. Rohan came to know that chlorine is more reactive than iodine. How can Rohan explain the observation made by his brother?

OR

2 mL of ethanoic acid was taken in each of test tube I and test tube II by a student. A red litmus paper was introduced in test tube I and a pH paper was introduced in test tube II. The student also added ethanol solution to each of the test tubes. Write down his observations and explain with the reactions where possible. 2 marks

Q24. The given figure illustrates multiple fission in Plasmodium. 2 marks

Is the genetic material of X different from Y? Support your answer with an appropriate reason.

Q25. A student obtained the given graph while performing an experiment to find the dependence of voltage (V) across a resistor on current (I) flowing through it.

Find the resistance of the resistor used in the experiment.

OR 2 marks

What is the equivalent resistance of the given system of resistors?

Q26. Sona is performing an activity to verify Archimedes' principle i.e. establishing the relationship between the loss in weight of the solid body and weight of water displaced when the solid body is fully immersed in the tap water. Which of the following observations made by Sona is (are) incorrect? I. The weight of the solid body as measured by the spring balance is least when it is completely immersed in the tap water. II. Force exerted by the tap water on the upper surface of the solid body is in the upward direction. III. The loss in weight of the solid is equal to the weight of the liquid displaced. 2 marks

Q27. Two beakers contain colourless solutions of magnesium oxide and carbon dioxide. How can the solutions in the beakers be identified? Only strips of red and blue litmus paper are available. 2 marks

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Grade X

Science Mock Test Solutions

Solution

1. When heated, limestone (calcium carbonate) decomposes to form calcium oxide and carbon dioxide.

2. According to the 10% law of energy transfer, only 10% of the energy stored at a particular trophic level is transferred to the next higher trophic level. Green plants utilise 1% of solar energy for photosynthesis. Of this energy stored in plants, only 10% is transferred to the primary consumers. This pattern is followed at each successive trophic level.

3. (a) On adding silver nitrate to copper, displacement reaction will take place. In this reaction, copper being more reactive than silver will replace silver from the solution. Cu + 2AgNO3 → Cu(NO3)2 + 2 Ag (b) Aluminium reacts with hydrochloric acid to liberate hydrogen gas. 2 Al + 6 HCl → 2 AlCl3 + 3 H2

4. Although helium has 2 valence electrons, it is not placed in the 2nd group because its valence shell is completely filled, and it is an inert gas. All elements having a complete valence shell are placed in the last group, i.e., group 18.

OR

Detergents are sodium salt of a long chain benzene sulphonic acid, which has cleansing properties in water. The detergents are prepared from linear hydrocarbons to make them easily biodegradable. The detergent entraps the dirt particles by attaching the hydrocarbon part of detergent to the greasy or oily particles. These greasy dirt particles then get

dispersed in water and the cloth gets cleaned.

5. The advantages of using LPG are as a source of energy are as follows: 1. Has a high calorific value of about 50 kJ/g 2. Does not cause pollution as it burns with a smokeless flame 3. Does not produce poisonous gases on burning 4. Easy to use and store 5. Neat and clean fuel

6. The child looks different from its parents because of two main reasons: ● The child obtains DNA from both the parents; thus obtaining different

characteristics of both. ● The DNA transferred from parents to offsprings is not exactly identical

because the copying of DNA is not accurate. As a result, the newly formed DNA results in some variations.

Variations are important because they allow the survival of a species in a wide range of environmental conditions. They lead to evolution.

7. (a) The principal focus of a concave mirror is the point on the principal axis on which light rays parallel to the principal axis meet after reflection. (b) To receive maximum solar energy, the cooker must be placed at the focal distance of the mirror. Here, Object distance, u = −∞ Image distance, v = f

Focal length, f , where R = radius of curvature

From mirror formula,

or, v = 5 m The cooker must be placed at 5 m from the optical centre of the mirror.

8. Metal X does not react with water at all. Hence, it is a very less reactive metal. Less reactive metals can be extracted from their sulphide ores in the following manner: Steps followed for extraction 1. Roasting: when heated in air, metal sulphide is converted to metal oxide

2. Metal oxide is then reduced to metal by further heating

3. The metal thus obtained is not very pure. Pure metal can be obtained by the process of electrorefining.

9. The functional group present in ethanol is alcohol (−OH). The structure of ethanol is shown below as:

The name of the gas which is evolved when a piece of sodium is added to ethanol is hydrogen. This reaction also results in the formation of another product i.e., sodium ethoxide. The balanced chemical equation for the given reaction is

Ethene can be obtained from ethanol by heating it at 443 K in the presence of excess concentrated sulphuric acid. The balanced chemical equation for the chemical reaction can be written as:

OR

(a). The chemical reaction that takes place in a soda acid fire extinguisher is:

(b). i. Tamarind − Tartaric acid ii. Oranges − Citric acid (c). Some uses of bleaching powder are: i. It is used for disinfecting water to make it germ-free. ii. It is used in the textile industry to bleach cotton and linen materials. iii. It is also used as an oxidizing agent in many industries.

10. (a) In the given figure, I → Hypothalamus II → Pituitary gland III → Midbrain IV→ Medulla (b) Hypothalamus − It is responsible for controlling body temperature, and the expression of emotional reactions. Pituitary gland − It controls and coordinates the endocrine system, and also secretes hormones like the growth hormone. Midbrain − It is concerned with the sense of right handedness and hearing. Medulla − It controls most of the involuntary actions such as heartbeat, blood pressure, etc.

11. (a) Let the equivalent resistance of R1 and R2 be R1.

It is given that, R1 = 9 Ω R2 = 18 Ω

Or, R1 = 6 Ω Hence, the equivalent resistance of the circuit = R1 + R3 = 6 + 6 = 12 Ω

Current flowing through the circuit I

Therefore, current through resistor R3 = 1 A Potential drop across R3, V3 = IR3 = 1 × 6 = 6 V (b) Energy is given by Power × Time. Energy used by TV = 250 × 1 = 250 Wh

Energy used by toaster Therefore, the toaster uses more energy is 15 minutes than the TV does in one hour.

12.

(a) The expected colour of flowers in their F1 progeny is blue. (b) 1/4 of the F2 generation have white flowers. So, we can calculate the percentage as follows: 1/4 × 100 = 25% Hence, the percentage of plants bearing white flowers in F2 progeny is 25. (c) The ratio of the genotype BB and Bw in the F2 progeny is 1 (BB) : 2 (Bw).

OR

(i) Evolution is not always equated with progress because evolution simply generates diversity, and this diversity helps in better adaptation and survival. (ii) Evolution creates complex body designs, but this does not imply that simpler forms are inefficient. For example, bacteria having simple organisation are more capable of surviving in extreme environments than organisms with

complex body designs. (iii) Human beings and chimpanzees have both evolved from a common primate ancestor, but there is no progress associated with the evolution of chimpanzees. (iv) Human beings should not be considered as the highest evolved species or the climax species. They are only a branch of evolution.

13. Least distance of distinct vision, d = 25 cm Therefore, object distance for clear vision, u = d = −25 cm The near point of the person’s eyes is 2 m. On using the required spectacles, the image distance, v = −2 m = −200 cm Let the focal length of the spectacle lens be f. On putting these values in the lens formula, we get

14. An AC generator is a machine that transforms mechanical energy into electrical energy for producing electric current or electricity.

Electric generator Working principle: When the coil is manually rotated in the anticlockwise direction, segment AB moves downward, thereby cutting the magnetic field lines near the north pole of the magnet; and segment CD moves upward, thereby cutting the magnetic field lines near the south pole of the magnet. As a result, a current is induced in these segments. Fleming’s right hand rule can be applied to find the direction of the induced current, which will flow from B to A and D to C. Segments AB and CD interchange their positions after half-a-revolution. In consequence, segment AB starts moving upward and segment CD starts moving downward. As a result, after half-a-revolution, the direction of the induced current in the coil gets reversed. Hence, the polarity of current changes in the coil after each half-revolution. The current that changes direction after equal intervals of time is called alternating current (AC). Hence, this device is called an AC generator.

15. (a) Coal and petroleum were formed from the degradation of biomass millions of years ago. The reserves of these resources are limited and they take a very long time to form. If these are not used judiciously, then they will soon get completely exhausted. (b) The four disadvantages of using coal and petroleum are as follows: i. Fossil fuels are exhaustible sources of energy. Therefore, they cannot fulfil our long-term energy requirements. ii. The carbon dioxide gas released because of the combustion of fossil fuels adds to global warming. iii. Carbon monoxide is a toxic gas that is released because of the incomplete combustion of fossil fuels. iv. The oxides of nitrogen and sulphur are released when fossil fuels are burnt. Apart from causing acid rains, these gases are also harmful for living beings.

OR

(a)

S. No AC generator DC generator

i. It produces alternating current. It produces direct current.

ii. It has two simple ring-type commutators.

It has a single split-ring commutator.

(b) “Brushes” are conducting stationary links between the rotating armature coil and the external circuit in electric generators and motors.

16. (a) Oxidation reaction; Combination reaction The given reaction is an oxidation reaction because carbon gains oxygen to form carbon dioxide. It is also a combination reaction as carbon and oxygen combine to form a single compound. (b) Decomposition reaction

The given reaction is a decomposition reaction because calcium carbonate decomposes to form two products, namely calcium oxide and carbon dioxide. (c) Displacement reaction The given reaction is a displacement reaction because lead displaces copper from copper (II) chloride to form lead chloride and copper metal. (d) Double displacement reaction The given reaction is a double displacement reaction because of the exchange of ions between sodium hydroxide and hydrochloric acid, which leads to the formation of two new compounds, namely sodium chloride and water. (e) Double displacement reaction The given reaction is a double displacement reaction because of the exchange of ions between lead nitrate and potassium iodide, which leads to the formation of two new compounds, namely lead iodide and potassium nitrate.

OR

(a) The main ore of aluminium is bauxite. Its formula is Al2O3.2H2O. (b) Purified bauxite, which is aluminium oxide Al2O3, is called alumina. Carbon is used as a reducing agent for the reduction of alumina. It is reduced by the process of electrolysis. It is melted in an iron tank which is lined with carbon from inside. (c) Alumina is dissolved in cryolite Na3AlF6 to reduce its melting point and make it a good conductor of electricity.

17. The transpirational pull or suction pressure facilitates transport of water to greater heights in plants during day time. The evaporation of water molecules from the leaf surface (stomata) is known as transpiration. It creates a suction pressure, as a result of which, water is forced into the xylem vessels of the roots. From the xylem vessels of the roots, water is transported to the xylem vessels of the stem. The water which is lost through the stomata in the leaves is replaced by water from the xylem vessels of the stem. Transpiration is important because of the following reasons:−

● The rate of transpiration greatly affects the rate of absorption. The

greater the rate of transpiration, greater is the rate of absorption. ● As a result of transpiration, a pull or suction pressure is generated

which helps in movement of water to the tops of tall trees. ● It also helps in the distribution of water throughout the plant body. ● Transpiration has a cooling effect on plants in the presence of excessive

solar energy. ● The plant body gets rid of excess water through transpiration.

OR

(a). The movement of a leg on touching a hot object is an example of reflex action where the response is sudden and does not involve any thinking. However, the movement of a leg during walking is an example of voluntary action involving conscious control by the brain. (b). Heat receptors on the skin of the leg transmit heat impulse to the sensory neurons which meet the relay neuron in the spinal cord. These relay neurons, in the spinal cord, transmit impulse to the motor neuron which further transmits the response to the effector muscles in the leg, resulting in sudden movement of the leg away from the object. (c). The spinal cord forms the meeting place for the nerve bundles in reflex arc on their way to the brain. The brain is aware of the signal and the response that has taken place. However, it has no role in the creation of the response.

18. (a) Testis is the male reproductive organ in humans that produces sperms and also secretes the testosterone hormone. Important functions of testosterone are as follows:

● Stimulates the development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles

● Stimulates muscular growth, growth of facial hair, low pitch voice, sperm production, etc.

(b)

(i) Fertilisation takes place in the fallopian tube (oviduct). (ii) Implantation of the fertilised egg occurs in the uterus. (c) The embryo develops inside the mother’s body for about nine months. Inside the uterus, the outer tissue surrounding the embryo develops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. They provide a large surface area for the exchange of oxygen and nutrients. There is a special tissue called placenta embedded in the uterine wall. The embryo receives the oxygen and nutrients from the mother’s blood via the placenta. The waste material produced by the embryo is removed through the placenta.

19. Soap molecules are sodium or potassium salts of long-chain carboxylic acids, whereas detergent molecules are ammonium or sulphonate salts of long-chain carboxylic acids. Cleansing action of soaps: The dirt present on clothes is organic in nature and is insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster. These micelles remain suspended in the water and, thus, the dust particles are easily rinsed away by water.

Soaps do not form lather in hard water because soap molecules react with calcium and magnesium ions present in hard water to form insoluble substance called scum, which remains after washing in water. Problems that arise due to the use of detergents instead of soaps are as follows: a) Being nonbiodegradable in nature, they get accumulated in the environment causing soil and water pollution. b) Their entry into the food chain leads to bioaccumulation in living beings and causes several health issues.

20. Refractive index of ethyl alcohol = 1.36 Velocity of light in air = 3 × 108 m/s Using the relation,

Refractive index of carbon disulphide = 1.33

Using the relation,

Refractive index of water = 1.33 Using the relation,

Therefore, the speed of light is the fastest in water.

21.

(a) We know that Here, V = Potential difference, W = Work done, C = Charge The potential difference across a point is independent of the nature of charge. It is given that V = 10 V C = 4 C W =? W = V × C = 10 × 4 = 40 J Thus, the work done in moving a 4 C negative change across a potential

difference of 10 V is 40 J. (b) The diagram of a circuit that may be used for verifying Ohm’s law can be represented as

(c) Substances are classified as electrical conductors and insulators on the basis of their resistivity. Conductors such as copper have resistivity of the order of 10−8 Ω m, whereas insulators have resistivity of the order of 1010 Ω m or more.

OR (a) Joule’s law of heating shows the relation between the heat produced (H) in a device having resistance (R), when a current (I) flows through it for time (t).

The heat produced in a wire is directly proportional to the

● square of the current flowing in the wire ● resistance of the wire ● time during which the current flows through the wire

(b) Two devices that work on the principle of Joule’s heating are: ● Electric iron ● Safety fuse

(c) Resistance, R = 10 Ω Time, t = 10 min = 10 × 60 = 600 s Applied voltage, V = 30 V From Ohm’s law, we have the relation: V= IR

Where I = Current

A Using Joule’s law of heating:

Hence, the heat produced by the given device in 10 minutes is 5.4 × 104 J.

22. Anuj will observe that the test leaf contains very little amount of starch. Such an observation is an outcome of presence of potassium hydroxide in the watch glass in which plant was placed. Potassium hydroxide is a chemical compound that is used for absorbing carbon dioxide. Carbon dioxide is important for the production of starch during the process of photosynthesis. The plant could not carry out photosynthesis in the absence of carbon dioxide. Hence, it contains very little starch.

OR For this experiment, it is to be noted that starch formation reduces as the covered area on a leaf increases. Thus, starch formation will be least in leaf I as larger portion of it is covered with black paper, which reduces the area available for the leaf to carry out photosynthesis. So, the sequence that correctly represents the starch formation in increasing order in the given leaves is .

23. Chlorine displaces iodine from potassium iodide solution. The displaced iodine dissolves in potassium chloride giving it a purple colouration. The reaction occuring can be represented as follows:

OR

The red litmus paper turns blue in basic solutions. So, the student will not observe anything on introducing red litmus paper in test tube I as it contains acidic solution. The pH paper gives orange colour on introducing it to test tube B. On adding ethanol to both the test tubes, esterification reaction will take place.

24. X and Y represent two daughter nuclei formed after multiple fission. All daughter cells formed as a result of multiple fission are identical. Therefore, genetic material of X and Y would be the same.

25. Resistance of the resistor used in the experiment is given by R=VIR=VI= Slope of V-I graph ⇒⇒R = 5−02−05-02-0 = 2.5 Ω Therefore, the resistance of the resistor is 2.5 Ω

OR

6 Ω and 4 Ω are in parallel.

R = 2.4 Ω 10 Ω and 2 Ω are in parallel.

R' = 1.67 Ω ∴ Net resistance of the given system of resistors = (R + R') = 2.4 Ω + 1.67 Ω = 3.07 Ω

26. Only the second observation made by Sona is incorrect because of the reason that the force applied by the water on the upper surface of the solid body is always in the downward direction not in the upward direction which is clearly shown in the below diagram,

Hence, only statement II is incorrect.

27. The solution that changes the colour of blue litmus paper to red is an acidic solution. Oxides of non-metals such as carbon are acidic. On the other hand, the solution that changes the colour of red litmus paper to blue is a basic solution. Oxides of metals such as magnesium are basic in nature..

Mock Test_Grade 10_QuestionMock Test_Grade 10_Solution