CBSE Sample Papers for Class 10 Science Set 10 with Solutions - #NCSOLVE 📚

Students must start practicing the questions from CBSE Sample Papers for Class 10 Science with Solutions Set 10 are designed as per the revised syllabus.

CBSE Sample Papers for Class 10 Science Set 10 with Solutions

Time: 3 Hrs.
Max. Marks: 80

General Instructions

• This question paper consists of 39 questions in 3 sections. Section A is Biology, Section B is Chemistry and Section C is Physics.
• 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

Question 1.
Which of the following constitute a food chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Answer:
(b) Grass, goat and human

Explanation:
Grass – Goat – Human makes a food chain, grass being the producer, goat being the primary consumer and human being the secondary consumer

Question 2.
Which are the correct statements related to respiration?
(i) Respiration takes place both in the presence and absence of oxygen.
(ii) Anaerobic respiration produces more energy compared to aerobic respiration.
(iii) Oxygen is used in the breakdown of glucose during aerobic respiration.
(iv) Carbon dioxide is produced as a by-product of respiration.
(v) Respiration occurs only in animals.

(a) (i), (iii), (iv)
(b) (ii), (iii), (iv)
(c) (iii), (iv), (v)
(d) (ii), (iv), (v)
Answer:
(a) (i), (iii), (iv)

Explanation:
The statements (i),(iii) and (iv) are correct because respiration can occur with or without oxygen, utilising oxygen in aerobic respiration to breakdown glucose, and carbon dioxide is a common by-product.

Question 3.
Select the group in w’hich all organisms reproduce by fission.
(a) Amoeba, Leishmania, Paramecium and Plasmodium
(b) Amoeba, bacteria, yeast, and Leishmania
(c) Bacteria, yeast, leech, and Paramecium
(d) Amoeba, leech, Plasmodium and Hydra
Answer:
(a) Amoeba, Leishmania, Paramecium and Plasmodium

Explanation:
Amoeba, Leishmania, Paramecium and Plasmodium occur in the same group because all of them perform fission.

Question 4.
Posture and balance of the body is controlled by
(a) cerebmm
(b) cerebellum
(c) medulla
(d) pons
Answer:
(b) cerebellum

Explanation:
Posture and balance are controlled by cerebellum.

Question 5.
Which blood vessel carries deoxygenated blood from the heart to the lungs?
(a) Pulmonary vein
(b) Aorta
(c) Pulmonary’ artery
(d) Superior vena cava
Answer:
(c) Pulmonary’ artery

Explanation:
Pulmonary artery carries deoxygenated blood from the heart to the lungs.

Students may confuse between arteries and veins. Arterics carry bLood away from the heart, while veins carry blood toward the heart.

Question 6.
Which of the following is a correct combination of environmental issue and its cause?
(a) Global warming : Excess release of greenhouse gases
(b) Acid rain : Increase in oxygen levels in the atmosphere
(c) Deforestation : Planting of more trees
(d) Ozone depletion : Reduction in CFCs
Answer:
(a) Global warming : Excess release of greenhouse gases

Explanation:
Global warming excess release of greenhouse gases is the correct combination as global warming is caused by the increased concentration of greenhouse gases like carbon dioxide in the atmosphere.

Question 7.
Which of the following gases is mainly responsible for the depletion of the ozone layer? [1]
(a) Carbon dioxide
(b) Chlorofluorocarbons (CFCs)
(c) Methane
(d) Nitrogen
Answer:
(b) Chlorofluorocarbons (CFCs)

Explanation:
CFCs are harmful chemicals released from air conditioners, refrigerators, and aerosol sprays that cause the depletion of the ozone layer in the atmosphere.

The following question consists of two statements – Assertion (A) and Reason (R). Answer these questions by 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 but (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 8.
Assertion (A) A neuron transmits message in one direction.
Reason (R) The response is slow and produced by all cells of target tissue. [1]
Answer:
(c) (A) is true but (R) is false.

Explanation:
A is true, but R is false. R can be corrected as
The response is rapid and produced only by cells connected to nervous system.

Question 9.
Assertion (A) In asexual reproduction, genetic variation among offspring is minimal.
Reason (R) Mechanisms like mutation and genetic recombination occur frequently during asexual reproduction. [1]
Answer:
(c) (A) is true but (R) is false.

Explanation:
A is true, but R is false. R can be corrected as Mechanisms like mutation and genetic recombination occur frequently during sexual reproduction.

Question 10.
Energy flow in a food chain is always unidirectional. Comment upon the statement with justification. [2]
Answer:
Energy flow in a food chain is always unidirectional because it moves in one direction from producers to consumers. Producers like plants capture solar energy and transfer it to herbivores when they are eaten. Then, the energy passes to carnivores when they consume herbivores. At each step, energy is lost as heat due to metabolic activities, so it cannot flow back to the previous level. Therefore, energy flows only in one direction and does not recycle in the food chain.

Question 11.
Attempt either A or B [2]
Respiration is the process by which living organisms breakdown glucose to release energy. This process can occur with or without oxygen in different organisms.
A. Name the type of respiration in the following organisms and mention the products formed.
(i) Yeast
(ii) Humans
Answer:
(i) Yeast performs anaerobic respiration, also called fermentation. The products formed are alcohol and carbon dioxide.
(ii) Humans perform aerobic respiration, where glucose is completely broken down in the presence of oxygen to produce carbon dioxide, water and energy.

Or

B. Explain the role of mitochondria in respiration.
Answer:
The role of mitochondra in respiration is to provide energy. During aerobic respiration, glucose is broken down in the presence of oxygen inside the mitochondria. This process releases energy in the form of ATP (adenosine triphosphate), which cells use to perform various functions necessary for life.

Question 12.
Certain hormones and glands involved in human endocrine system are listed below [2]
Thyroid gland, insulin, adrenal gland, glucagon, pituitary gland, testosterone, ovaries.
Identify the organ referred to as the master gland and the small gland situated above each kidney and mention the hormone they produce along with their functions.
Answer:
The glands are identified as pituitary gland adrenal gland, respectively.

GLAND	HORMONE	FUNCTION
Pituitary gland (Master gland)	Growth hormone	The growth hormone secreted by the pituitary gland, stimulates the growth of bones and muscles and helps in overall body development.
Adrenal gland (gland situated above kidneys)	Adrenaline	The function of adrenaline is to prepare the body for ‘fight or flight’ response during stressful or emergency situations by increasing heart rate, blood pressure, breathing rate, and energy supply.

Question 13.
Draw the structure of neuron and explain impulse transmission through a neuron. [3]
Answer:
Nerve cells or neurons help in transmitting messages called nerve impulses throughout the body. The process starts when dendrites receive a signal from a sensory organ or another neuron. This signal is passed to the cell body, and then travels down the axon in the form of an electrical impulse. When the impulse reaches the axon terminals, it cannot be transmitted directly to the next neuron.

Therefore at the gap between two neurons known as synapse, the impulse triggers the release of special chemical messengers called neurotransmitters. These chemicals carry the message across the synapse to the dendrites of the next neuron, continuing the transmission. This synchronised chain of events helps carry messages quickly from one part of the body to another.

Question 14.
“While studying biology, Am an read that dimples in the cheeks appear when a dominant gene is present.
This gene is located on a thread-like structure inside the nucleus, which carries information for many such features. In Aman’s family, his father has dimples, but his mother does not.” [3]
(i) Define trait?
(ii) From the situation, name the thread-like structures that carry genes and explain their role in heredity.
Answer:
(i) A trait is a feature or characteristic of a living organism, such as the colour of eyes, height, or the shape of seeds. These traits are passed on from parents to their offspring through genes, which makes children resemble their parents in many ways.

(ii) Chromosomes are tiny thread-like structures found inside the nucleus of a cell. They carry genes, which are the basic units of heredity. During reproduction, chromosomes are passed from both father and mother to the offspring. This transfer of chromosomes ensures that the child inherits different traits from both parents, helping in the continuity of species and creating variation among individuals.

Question 15.
Neha is studying how living organisms remove waste products from their bodies to maintain health and balance. She wants to learn about different excretory organs, how they function, and the reasons behind certain natural phenomena related to excretion. Help her by answering the questions given below. [4]
Attempt either subpart A or B
A. Explain why a person might have high levels of urea in their blood.
Answer:
A person may have high levels of urea in their blood if the kidneys are not working properly. When kidneys fail, they cannot filter out urea and other wastes from the blood, causing urea to build up.

Or

B. Describe the path of urine formation through the nephron.
Answer:
In the nephron, blood is filtered in the glomerulus and useful substances are reabsorbed in the tubules. The remaining waste forms urine, which passes to the collecting duct and then to the bladder

C. Differentiate between the kidneys and lungs as excretory organs in humans.
Answer:
Kidneys and lungs are both excretory organs but remove different wastes. Kidneys remove nitrogenous wastes like urea, excess salts and water from the blood in the form of urine. Lungs remove carbon dioxide and water vapour from the body through exhalation. Thus, kidneys remove solid and liquid wastes, while lungs remove gaseous wastes.

D. The figure given below shows the structure of a nephron with parts labelled as A, B, C and D.
Identify the part where the filtration of blood takes place.

Answer:
The given figure represents the structure of a nephron with parts labelled as A, B, C and D. Out of these the part labelled B is the glomerulus where filtration of blood takes place.

Question 16.
Attempt either A or B
A. Mrs. Sarita explained that flowering plants reproduce by pollination, where pollen from the male part reaches the female part. This is important for seed and fruit formation. 15]
(i) When does a pollen tube develop in a flower?
(ii) How does wind help in pollination?
Answer:
(i) The pollen tube develops after a pollen grain falls on the stigma of a flower. The pollen grain then absorbs moisture and nutrients from the stigma and starts growing a tube called the pollen tube. This tube grows down through the style towards the ovary and finally reaches the ovule. The pollen tube helps the male gamete travel safely to the female gamete for fertilisation to occur inside the ovule.

(ii) Wind helps in pollination by carrying pollen grains from the anther of one flower to the stigma of another flower. This process is called wind pollination. Wind pollination allows plants to reproduce even if insects or animals are not present. The pollen grains are usually light and smooth to be easily carried by the wind.

Or

B. Neha observed flowers in her garden and learned about pollination.
(i) What is the role of agents like wind, water or animals in the process of pollination?
(ii) Name two changes that occur in a flower after fertilisation.
Answer:
(i) Agents like wind, water or animals play an important role in pollination. They carry pollen grains from the anther of one flower to the stigma of another flower, while searching for nectar. This transfer of pollen is necessary for fertilisation to take place in plants. Without these agents many plants would not be able to reproduce and form seeds or fruits.

(ii) After fertilisation occurs in a flower, the ovary starts to develop into a fruit. The ovules inside the ovary develop into seeds. At the same time, other parts of the flower like petals, stamens, and style usually wither and fall off. These changes help in the protection and dispersal of seeds for the growth of new plants.

Section – B

Question 17.
Which of the following salts has no water of crystallisation? [1]
(a) Blue vitriol
(b) Washing soda
(c) Baking soda
(d) Gypsum
Answer:
(c) Baking soda

Explanation:
Among the given option, baking soda (NaHCO₃) has no water of crystallisation.

Question 18.
Which of the following equations represent redox reactions and what are the values for ‘p’ and ‘q’? [1]
Equation 1 : CuO + H₂ → pCu + qH₂O
Equation 2 : NaOH(aq) + HNO₃(aq) → NaN03(fl(y) + H₂O(l)
(a) Only equation 1 is a redox reaction, p = 1 and q = 1
(b) Both equations 1 and 2 are redox reactions, p = 2 and q = 10
(c) Only equation 2 is a redox reaction, p = 1 and q = 1
(d) Neither equation 1 nor 2 is a redox reaction
Answer:
(a) Only equation 1 is a redox reaction, p = 1 and q = 1

Explanation:
Only equation 1 is a redox reaction, p = l and cl = 1 In equation 1, H₂ is getting oxidised and CuO is getting reduced.
Equation 2 is a neutralisation reaction with no change in oxidation states.

A redox reaction is a chemical reaction in which oxidation and reduction occur simultaneously.

Question 19.
Four statements about corrosion and prevention are listed below: [1]
L Rusting of iron is accelerated in salty water.
II. Galvanisation is coating iron with a thin layer of zinc to prevent rusting.
III. Painting or greasing prevents iron from rusting by forming a protective layer.
IV. Aluminium corrodes rapidly in moist air because its oxide layer is porous.

Which statements are correct?
(a) I and II
(b) II and IV
(c) I and III
(d) I, II and III
Answer:
(d) I, II and III

Explanation:
I, II and III – Rusting accelerates in salty water, and galvanisation or painting prevents it. Aluminium does not corrode rapidly due to its protective oxide layer. Hence, statement IV is incorrect.

Question 20.
The chemical reaction between copper and oxygen can be categorised as [1]
(a) displacement reaction
(b) decomposition reaction
(c) combination reaction
(d) double displacemept reaction
Answer:
(c) combination reaction

Explanation:
The chemical reaction between copper and oxygen can be written as

As oxygen and copper combines to form a single compound copper oxide, hence, the given reaction is a combination reaction.

Question 21.
Which element among the following can be considered as a metal and non-metal both? [1]
(a) Nitrogen
(b) Sulphur
(c) Silicon
(d) Mercury
Answer:
(c) Silicon

Explanation:
Silicon is a metalloid, as it can react with an acid and base both.

Question 22.
pH is a scale used to express the concentration of hydrogen ions (H⁺) in a solution. Four samples of common household substances were tested with universal indicator. The pH values are shown below. Which sample could be a solution of baking soda? [1]

Sample	pH value
(a) A	2
(b) B	7
(c) C	9
(d) D	12

Answer:
(c)

Explanation:
Baking soda is mildly basic with a pH around 8-9.

Question 23.
Carbon forms a large number of compounds because [1]
(a) carbon atoms are small and cannot form strong bonds.
(b) carbon atoms can form single, double, and triple covalent bonds and show catenation.
(c) carbon can only bond with hydrogen.
(d) carbon atoms easily form ionic bonds with metals.
Answer:
(b) carbon atoms can form single, double, and triple covalent bonds and show catenation.

Explanation:
Carbon atoms can form single, double and triple covalent bonds and show catenation.

The following question consists of two statements — Assertion (A) and Reason (R). Answer these questions by 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 but (R) is not the correct explanation of (A).
(c) (A) is tme but (R) is false.
(d) (A) is false but (R) is tme.

Question 24.
Assertion (A) Sodium hydrogen carbonate is used as an ingredient in antacids. [1]
Reason (R) NaHCO₃ is a mild non-corrosive basic salt.
Answer:
(a) Both (A) and (R) are true and (R) is a correct explanation of (A).

Explanation:
NaHCO₃ is a mild base with pH slightly above 7 it reacts with the excess acid in our stomach and neutralise it.

Question 25.
Riya performed an activity in the science lab as demonstrated by her teacher. She added concentrated sulphuric acid to a test tube containing solid sodium chloride and quickly closed it with a cork fitted with a delivery tube. The other end of the tube was directed towards moist blue litmus paper. She also noticed that the teacher connected a guard tube containing calcium chloride before the gas reached the litmus paper. [2]

Answer the following questions based on this activity:
(a) What change will Riya observe on the moist blue litmus paper? Name the gas responsible for this change.
(b) Why is the gas first passed through a guard tube containing calcium chloride before reaching the litmus paper?
Answer:
(a) The moist blue litmus paper turns red because hydrogen chloride (HC1) gas is released, which is acidic in nature and shows its acidic property only in the presence of moisture.
NaCl + H₂SO₄ → NaHSO₄ + HCl ↑

(b) The gas is first passed through a guard tube containing calcium chloride to remove any moisture so that the HC1 gas remains dry before reaching the litmus paper.
To score maximum marks, always mention that HCl gas shows acidity only in the presence of moisture and write the balanced reaction in your answer.

Question 26.
Attempt either A or B.
A. During extraction of metals, electrolytic refining is used to obtain pure metals. [3]
(a) Which material will be used as anode and cathode for refining of silver metal by this process?
(b) Suggest a suitable electrolyte also.
(c) In this electrolytic cell, where do we get pure silver after passing electric current?
Answer:
(a) Anode Impure block of silver metal. Cathode Pure thin strip of silver metal.
(b) Aqueous solution of a silver salt like AgNO, can be used as an electrolyte.
(c) We get pure silver at cathode, because at cathode, reduction reaction will take place.
Ag₊ (aq) + e_– → Ag (s)

Dont’t make the common mistake mistake by writing that oxidation occurs at the cathode, or by taking pure silver as anode, or by using the wrong eLectroLyte Like NaCl solution.

Or

B. State giving reason the reduction process to obtain the following metals from their compounds.
(a) Mercury
(b) Copper and
(c) Sodium
Answer:
(a) Mercury (Hg) is a less reactive metal. It is obtained simply by heating their oxides.

(b) Copper (Cu) is also a less reactive metal. It is found in sulphide ore (Copper glance) which on oxidation forms copper oxide, which further on self reduction or auto-reduction process give Cu metal.

(c) Sodium (Na) is highly reactive metal, so it obtained by electrolytic reduction of molten ores, e.g. in NaCl.

At cathode, Na⁺ + e^– → Na
At anode 2Cl^– → Cl₂ + 2e^–

Question 27.
In a laboratory activity to study the reaction of acids with hydrogencarbonates, a chemist carefully added dilute hydrochloric acid (HCl) to a test tube containing baking soda (sodium hydrogen carbonate, NaHCO₃. [3]

A colourless gas was immediately evolved, and a new salt X was formed in the test tube. The gas was passed through fresh lime water using a delivery tube, and after some time, the lime water turned milky.
Answer the following questions based on the information given above
(a) Identify salt ‘X’ and the gas evolved.
(b) Describe the experiment shown in the figure.
(c) Write the balanced chemical reaction involved in the process.
Answer:
(a) The salt X formed is sodium chloride (NaCl) and the gas evolved is carbon dioxide (CO₂).
(b) The experiment shown is about when a metal hydrogen carbonate reacts with acid, it forms salt and water along with carbon dioxide gas. This carbon dioxide produced turns lime water milky when passed through it.
(c) Reaction involved are

Question 28.
Two students decided to investigate the effect of water and air on an iron object under identical experimental conditions. They measured the mass of each object before placing it partially immersed in 10 mL of water. After a few days, the objects were removed, dried, and their masses were measured. The table shows their results: [4]

Student	Object	Mass of object before rusting in g	Mass of the coated object in g
A.	Nail	3.0	3.15
B.	Thin plate	6.0	6.33

A. Which of the following is the correct reason for the difference in the increase in mass of the two iron objects?
(a) Nail rusts faster due to small size.
(b) Thin plate has more surface area, so more rust forms.
(c) Rusting depends only on the mass of iron.
Justify your answer.
Answer:
(b) Thin plate has more surface area, so more rust forms.

Explanation:
Thin plate has more surface area, so more rust forms. Rusting occurs faster on objects with larger surface area exposed to air and moisture.

B. In another experiment, the students coated iron nails with zinc and observed that rusting did not occur even when the nails were slightly scratched. What is the process of coating iron with zinc called, and why is zinc used for this purpose?
Answer:
The process is called galvanisation, where iron is coated with zinc because zinc is more reactive than iron and provides sacrificial protection even if the coating is scratched.

Or

During the same experiment, one student suggested using alloying instead of zinc for coating the iron nail. Will this protect the iron from rusting?
Answer:
Yes, alloying will prevent rusting of iron.
Alloying helps by modifying properties of the original metal.

C. Out of the following, which iron object would rust the fastest and why?
(a) Iron bucket electroplated with zinc ;
(b) Electricity cables having iron wires covered with aluminium
(c) Iron hinges on a gate
(d) Painted iron fence
Answer:
(c) Iron hinges on a gate

Explanation:
Iron hinges on a gate would rust the fastest because they are directly exposed to air and moisture without any protective coating.

Question 29.
Attempt either A or B. [5]
A. (a) Describe the addition reaction of carbon compounds with its application.
(b) State the function of catalyst used in the above reaction.
(c) How this reaction is different from a substitution reaction? Explain with an example.
Answer:
(a) The addition of hydrogen to an unsaturated molecule (C„ H2n) to make it saturated is known as hydrogenation or addition reaction.

(ii) This reaction is applied to convert unsaturated vegetable oil to saturated ghee.

The rate of reaction increases in the presence of catalyst (Ni or Pt). This is an addition reaction. [1]
(iii) In substitution reaction, a reagent substitutes an atom or a group of atoms from the reactant instead of addition.

Or

B. (a) State the litmus test to distinguish between an alcohol and a carboxylic acid.
(b) Give the equation for the reaction of a carboxylic acid with an alcohol. State the condition for the reaction and name the product formed. Name the reaction.
(c) Write a reaction which is reverse of this reaction? Mention the conditions required for the reaction. Name and write the use of this reaction.
Answer:
(a) Take 2 mL of alcohol and carboxylic acid in two test tube A and B. Put 1 drop of blue litmus in each of the test tubes, the liquid which shows no effect is alcohol whereas the liquid which turns it into red is carboxylic acid. [1]
(b) When ethanol (an alcohol) reacts with acetic acid (a carboxylic acid), a fruity smelling liquid called ester is obtained. This reaction is called esterification.

(c) The reverse of esterification is saponification. In this, ester is converted back to alcohol and salt of carboxylic acid by treating the ester with an alkali.

The above reaction is used in the preparation of soap.

Section – C

Question 30.
Choose the correct setup of protractor for tracing the path of ray of light through a glass prism, for measuring the angle of incidence? [1]

Answer:
(a) As angle of incidence is the angle between the incident ray and normal drawn on the refracting surface.

Question 31.
Riya is revising the concept of electric power and makes the following observations: [1]
I. Electric power is the rate at which electric energy is consumed in a circuit.
II. Power can be expressed as P = I R or P = \(\frac{V^2}{R}\)
III. SI unit of electric power is kilowatt.
Choose from the following the correct option:
(a) I and II
(b) I and III
(c) II and III
(d) I, II and III
Answer:
(a) I and II
Statements I and II are correct. SI unit of power is watt, not kilowatt. 1 kilowatt = 1000 watts, used for larger appliances.

The following question consists of two statements – Assertion (A) and Reason (R). Answer the question by 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 but (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 32.
Assertion (A) A ray incident along normal to the mirror retraces its path.
Reason (R) In reflection angle of incidence is always equal to angle of reflection. [1]
Answer:
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

Explanation:
When light ray incident along normal to the mirror, angle of incidence angle ∠i = 0°
According to law of reflection ∠i = ∠r, therefore angle of reflection ∠r = 0°, i.e. the incident ray retraces path.

Question 33.

The above image shows a thin lens of focal length 5 m.
(i) What type of lens is represented in the given figure?
Answer:
Convex lens

(ii) A real and inverted image is formed by this lens at a distance of 7 m. from its optical units calculate, with the help of lens formula, where the object should be positioned.
Answer:
\(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\)
In this case, n = 7m and f = 5 m.
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
The object will be placed 17.5 m on the left of the convex lens.

(iii) Draw a neatly labelled ray diagram to show the image formation described in part (ii).
Answer:

Question 34.
Attempt either A or B

A. In the given electric circuit, a 6V battery is connected to three resistors of 30 Ω, 10 Ω and 5 Ω arranged in parallel. Calculate:
(i) The current flowing through each resistor and equivalent resistance of the circuit.
Answer:
Current through each resistor,
I₁ = \(\frac{V}{R_1}=\frac{6}{5}\) = 1.2 A
I₂ = \(\frac{V}{R_2}=\frac{6}{10}\) = 0.6 A
I₃ = \(\frac{V}{R_3}=\frac{6}{30}\) = 0.2 A
R₁ = 5 Ω, R₂ = 10 Ω and R₃ = 30 Ω are connected in parallel, so their equivalent resistance,
\(\frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}\)
\(\frac{1}{R}=\frac{1}{5}+\frac{1}{10}+\frac{1}{30}\)
⇒ \(\frac{1}{R}=\frac{1}{3}\)
R = 3 Ω

(ii) The total current drawn from the battery.
Answer:
Total current drawn from the battery,
I = I₁ + I₂ + I₃
= 12 + 0.6 + 0.2
I = 20 A

Or

B. Find out the following in the circuit given in the figure.
(i) Calculate the equivalent resistance between points P and R.
(ii) If a potential difference of 4 V is applied between P and R, calculate the total current flowing through the circuit.
Answer:
(i) equivalent resistance of each parallel pair
R_parallel = \(\frac{R \times R}{R+R}=\frac{8 \times 8}{8+8}=\frac{64}{16}\) = 4 Ω
So, both parallel combinations (PQ and QR) give:
R_PQ= 4 Ω and R_QR = 4 Ω
Now, Add the two equivalent resistances in series:
R_Total = R_PQ + R_QR
= 4Ω + 4Ω
= 8 Ω

(ii) Total current through the circuit
I = \(=\frac{V}{R}=\frac{4 V}{8 \Omega}\) = 0.5 A

Current through the circuit = 0.5 A

Question 35.
Given figure shows a ray of light meeting the glass of the window of a car at an angle of incidence of 40°. [3]

(i) Assuming that the refracting index of glass is 1.5, find the angle of refraction for this ray in the glass.
Answer:
Applying Snell’s law, let r be the angle of refraction.
Given, i = 40°, n = 1.5
∴ Refractive index, n = \(\frac{\sin i}{\sin r}\)
sin r = \(\frac{\sin i}{n}=\frac{\sin 40^{\circ}}{1.5}\)
r = 25.37°

(ii) Complete the diagram by sketching the path of the ray through the glass and out on the other side.
Answer:

Question 36.
A lens produces a virtual image between the object and the lens. [3]
(i) Name the lens.
(ii) Draw a ray diagram to show the formation of this image.
Answer:
(i) The lens is concave lens.
(ii) The ray diagram is given below.

Question 37.
A student placed a plotting compass inside a solenoid and compass needle is pointed in the direction of flow of current in the solenoid. Based on the information from the above case answer the following questions. [3]
(i) Draw the diagram by drawing arrow heads to indicate the direction of the current flow. Describe the direction of the magnetic field inside the solenoid.
(ii) If key K is opened, what will happen to the compass needle?
Answer:
(i) As the current flows from the positive terminal to the negative terminal, so current flows in solenoid as shown below.

The direction of the magnetic field inside the solenoid always points from the induced south-pole towards the induced North-pole.
In the above case, direction of magnetic field is from left to right.

(ii) If the key K is opened, the current in solenoid coil becomes zero and the uniform magnetic field produced on the axis of solenoid will vanish. However, the compass needle will point in the direction North due to earth’s magnetic field.

Question 38.
Gopi has taken a straight conductor. He has allowed to flow a current / through it. He wants to know the variation of magnetic field B at a distance r from it. State how the magnetic field produced by a straight current-carrying conductor at a point depends on
A. Current flowing through the conductor?
Answer:
Strength of magnetic field B produced by a straight current-carrying conductor at a given point is
directly proportional to the current flowing through it,
i.e. B ∝ I [where, I = current]

B. distance of point from the conductor? [4]
Answer:
inversely proportional to the distance of that point from the wire,
i.e. B ∝ \(\frac {1}{r}\)
[where, r = distance between wire and point of observation]

Attempt either C or D
C. let the magnetic field B due to current I be 0.4 T. Then, what will be the magnetic field when the currer1t flowing through the wire becomes \(\frac {I}{2}\) ?
Answer:
Given, B₁ = 0.4 T, I₁ = I
B₂ = ?,
As B ∝ I
∴ \(\frac{B_2}{B_1}=\frac{I_2}{I_1}\) ……(i)
∴ From Eq. (i), we get
\(\frac{B_2}{0.4}=\frac{I / 2}{I}=\frac{1}{2}\)
∴ B₂ = \(\) × 0.4 = 0.2 T
Hence, the new magnetic field becomes 0.2 T.

Or

D. Name and state the rule for determining the direction of force on a current carrying conductor in a magnetic field.

Answer:
The state rule for determining the direction of force on a current carrying conductor in a magnetic field is given by Fleming’s left hand rule. According to this rule, if you align your thumb, index finger and middle finger of your left hand perpendicular to each other, where the index finger points in the direction of the magnetic field (from North to South), the middle finger points in the direction of the current (from positive to negative) then the thumb will point in the direction of the force experienced by the conductor.

Student may apply the left hand rule incorrectly by not keeping the fingers mentally perpendicular or by misidentifyingthe directions of magnetic field, current, and force.

Question 39.
Attempt either A or B

A. The circuit given below comprises of three resistances R₁, R₂ and R₃ joined and connected to a battery an ammeter A, a voltmeter V and a plug key K. The key K is closed and the voltmeter and ammeter readings are recorded.
(i) Name the combination in which the resistances are connected.
(ii) 110w will you conclude that the same potential difference (voltage) exists across three resistors connected to a battery?
(iii) Write one advantage of parallel combination and name the combination in which the ammeter is connected.
Answer:
(i) The combination in which the resistances are connected is parallel combination.

(ii) Close the key K and record the readings of ammeter and voltmeter for combination circuit. Now, keep the key K open and remove the ammeter and voltmeter from the circuit and insert the voltmeter in parallel and ammeter in series with the resistor R₁, as shown in figure below. Again, the voltmeter and ammeter readings are recorded

Similarly, measure the potential differences across resistances, R₂ and R₃. It is found that voltmeter gives identical reading which leads to conclude that the voltage or potential difference across each resistor is same and is equal to the potential difference across the combination.

(iii) One advantage of a parallel circuit is that if one electrical appliance stops working due to some defect, then all other appliances keep working normally and each appliance gets the same voltage as that of the power supply line and the combination in which the ammeter in the circuit is connected in series combination

Clearly explain how equal voltmeter readings across resistor prove parallel combination and support it with a labelled diagram.

Or

B. (i) Three resistors of resistance 1 Ω, 2 Ω, 3 Ω are combined in series. What is the total resistance of the combination?
(ii) If the combination is connected to a battery of emf 12 V and negligible internal resistance. Obtain current in the circuit.
(iii) Find out potential difference across each resistor.

Answer:
(i) R₁ = 1 Ω, R₂ = 2 Ω and R₃ = 3Ω
In series combination,
R_eq = R₁ 1 + R₂ + R₃
R_eq = 1 + 2 + 3
R_eq = 6 Ω

(ii) Current flowing through the circuit = I
Emf of the battery, E = 12 V
Total resistance, R_eq = 6 Ω
Ohm’s law, I = \(\frac{E}{R}=\frac{12}{6}\) = 2A

(iii) The potential drop across 1 Ω = V₁
then, V₁ = 2 × 1 = 2 V
Potential drop across 2 Ω = V₂
V₂ = 2 × 2 = 4V
Again, potential drop across, 3 Ω = V₃
V₃ = 2 × 3 = 6V
So, for 1 Ω is 2 V, 2 Ω is for 4 and 3 Ω is 6 V.

The post CBSE Sample Papers for Class 10 Science Set 10 with Solutions appeared first on Learn CBSE.

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