CBSE Class 10 Science Answer Key 2021-22

CBSE Class 10 Science Answer Key 2021-22 – The Central Board of Secondary Education has conducted the term one examination for class 10th from November 18 to December 12, 2021. Candidates who have written the examination can check their CBSE Class 10 Science Question Paper and Answer Key from this page. The Science examination has been conducted on December 2, 2021.

Ques. A student took Sodium Sulphate Solution in a test tube and added Barium Chloride Solution to it. He observed that an insoluble substance has been formed. The color and molecular formula of the insoluble substance is:
Ans. White, BaSO4

Ques. Which of the following oxide(s) is/are soluble in water to form alkaline?
Ans– a) (i) and (iii)

Ques. Study the diagram given below and identify the gas formed in the reaction.
Ans– d) Hydrogen which while burning produces a popping sound.

Ques. Sodium reacts with water to form sodium hydroxide and hydrogen The balanced equation which represents the above reaction is :
Ans- b) 2Na(s) + 2H2O(l)-> 2NaOH(aq) + H2(g)

Ques. Which of the options in the given table are correct?

Ans- c) (ii) and (iii)

Ques. C₆H₁₂O₆(aq) + 6O₂(aq) -> 6CO₂(aq) + 6H2O(l)
The above reaction is a/an
Ans- c) exothermic reaction

Ques. Which of the following statement about the reaction given below is correct? MnO₂ + 4HCl -> MnCl₂ + 2H₂O + Cl₂
(i) HCl is oxidised to Cl₂
(ii) MnO, is reduced to MnCl₂
(iii) MnCl₂ acts as an oxidising agent
(iv) HCl acts as an oxidising agent
Ans-  c) (i) and (ii) only

Ques. Select from the following the statement which is true for bases. 
Ans- d) Bases turn pink when a drop of phenolphthalein is added to them.

Ques. Study the following table and choose the correct option:

Ans- d)

Ques. It is important to balance the chemical equations to satisfy the law of conservative of mass. Which of the following statement of the law is incorrect?
Ans- c) The chemical composition of the reactants is the same before and after the reaction.

Ques. Consider the following statement in connection with the functions of the blood vessels marked A and B in the diagram of a human heart as shown.
i) Blood vessel A – it carries carbon dioxide rich blood to the lungs.
ii) Blood vessel B – it carries oxygen rich blood from the lungs.
iii) Blood vessel B – left atrium relaxes as it receives blood from this blood vessel
iv) Blood vessel A – right atrium has thick muscular wall as it has to pump blood to this blood vessel.
Ans- d) (i) (ii) and (iii)

Ques. In living organisms during respiration which of the following products are not formed if oxygen is not available?
Ans- a) carbon dioxide + water

Ques. The correct statement with reference to single celled organisms are 
i) Complex substances as not broken down into simpler substances.
ii) Simple diffusion is sufficient to meet the requirement of exchange of gases.
iii) Specialized issues perform different functions in the organism.
iv) Entire surface of the organism is in contact with the environment for taking in food.
Ans- c) (ii) (iv)

Ques. Which one among the following is not removed as a waste product from the body of a plant?
Ans- b) urea

Ques. Which of the following statement are correct in reference to the role of A (shown in the given diagram) during a breathing cycle in human beings?
i) It helps to decrease the residual volume of air in lungs.
ii) it flatens as we inhale.
iii) it gets raised as we inhale.
iv) it helps the chest cavity to become larger
Ans- (ii) and (iv)

Ques. Which one of the following conditions is true for the state of stomata of a green leaf shown in the given diagram?
Ans- c) Large amount of water flows out from the guard cells.

Ques. In which of the following is a concave mirror used?
Ans- a solar cooker

Ques. A student wants to obtain a magnified image of an object AB as on a screen. Which one of the following arrangements shows the correct position of AB for him /her to be successful?
Ans- c)

Ques. The following diagram shows the use of an optical device to perform an experiment of light. As per the arrangement shown, the optical device is likely to be a:
Ans- b) Concave lens

Ques. A ray of light starting from air passes through medium A of refractive index 1.50 enters medium B of refractive index 1.33 and finally enters medium C of refractive index 2.42. If this ray emerges out in air from C, then for which of the following pairs of media the bending of light is least?
Ans- b) A-B

Ques. Which of the following statement is not true for scattering of light?
Ans- c) Scattering of light takes place as various colours of white light travel with different speed in air.

Ques. For the diagram shown according to the new Cartesian sign convention the magnification of the image formed will have the following specifications: 
Ans- b) Sign – Positive, Value- More than 1

Ques. A ray of light is incident as shown. If A, B and C are three different transparent media, then which among the following options is true for the given diagram?
Ans- c) <3 =<2

Ques. In the diagram given below, X and Y are the end colours of the spectrum of white light. The colour of ‘Y’ represents the 
Ans- colour used to paint the danger signals.

Ques. Which one of the following reactions is categorized as thermal decomposition reaction?
Ans- d) CaCO3(s) -> Cal(s) + CO2(g)

Ques. Consider the PH value of the following acidic samples: 

The decreasing order of their H+ ion concentration is 
Ans- c) 2>1>4>3

Ques. Study the experimental set up shown in given figure and choose the correct option from the following:
Ans- d)

Ques. Which one of the following structures correctly depicts the compound CaCl2?
Ans- a)

Ques. The pair(s) which will show displacement reaction is/are
i) Nacl solution and copper metal
ii) AgNO3 solution as copper metal
iii) Al(SO4)3 solution and magnesium metal
iv) ZnSO4 solution and iron metal
Ans- b) (ii) and (iii)

Ques. Which of the following salts do not have water crystallisation?
i) Bleaching powder 
ii) plaster of Paris
iii) washing soda
iv) baking soda
Ans-  d) (i) and (iv)

Ques. Assertion (A) : Sodium hydrogen carbonate is used as an ingredient in antacids.
Reason (R)    NaHCO3 is a mild non- corrosive basic salt.
Ans – a) both (A) and (R) are true and (R ) is the correct explanation of (A)

Ques. (A) Burning of Natural gas in an endothermic process.
(R) Methane gas combines with oxygen to produce carbon dioxide and water
Ans- d) (A) is false but (R ) is true.

Ques. (A) Nitrogen is an essential element for plant growth and is taken up by plates in the form of inorganic nitrates or nitrites.
(R) The soil is the nearest and richest source of raw materials like Nitrogen, Phosphorus and other minerals for the plants.
Ans- b) Both (A) and (R ) are true but (R ) is not correct explanation of (A)

Ques (A) Sun appears reddish at the time of Sunrise and Sunset.
(R) Distance travelled by sunlight in the atmosphere is lesser during sunrise and sunset compared to noon.
Ans- c) (A) is true but (R)  is false

Ques. (A) Hydrochloric acid helps in the digestion of food in the stomach. 
(R) Hydrochloric acid creates an acidic medium to activate protein-digesting enzymes.
Ans- a) both (A) and (R) are true and (R ) is the correct explanation of (A)

Ques. A student was asked to write a stepwise procedure to demonstrate that carbon dioxide is necessary for photosynthesis. He wrote the following steps. The wrongly worded step is – 
Ans- b) Bottom of the bell jars is sealed to make them air tight.

Ques. Respiratory structure of two different animals – a fish and a human being are as shown. 

Ans- b) both have thin and moist surface for gaseous exchange.

Ques. observe the diagram of an activity given below. What does it help to connclude, when the person exhales into the test-tube?
Ans- c) Percentage of carbon dioxide is more in the exhaled air. 

Ques. If a lens can converge the sun rays at a point 20cm away from its optical centre, the power of this lens is – 
Ans- +5D

Ques. The radius of curvature of a converging mirror is 30cm. At what distance from the mirror should an object be placed so as to obtain a virtual image?
Ans- d) Between 0cm and 15cm

Ques. The length of small intestine in a deer is more as compared to the length of small intestine of a tiger. The reason for this is – 
Ans- b) type of food consumed.

Ques. Identify the two components of Phloem tissue that help in transportation of food in plants.
Ans- Sieve tubes & companion cells

Ques. A converging lens forms a three times magnified image of an object which can be take on a screen. If the focal length of the lens is 30cm then the distance of the object from the lens is 
Ans – d) -40cm

Ques. Which of the following statements is not true in reference to the diagram shown above?
Ans- b) Image formed is enlarged

Ques. In the diagram shown above n1 and n2 and n3 are refractive indices of the media 1, 2 and 3 respectively. Which one of the following is true in this case?
Ans- d) n3>n1

Ques. The refractive index of medium A is 1.5 and that of medium B is 1.33. If the speed of light in air is 3×10⁸ m/s what is the speed of light in medium A and B respectively?
Ans- d) 2× 10⁸ m/s and 2.25 × 10⁸ m/s

Ques. An object of height 4cm is kept at a distance of 30cm from the pole of a diverging mirror. If the focal length of the mirror is 10cm, the height of the image formed is 
Ans- c) +1.0cm

Ques. 50.0 mL of tap water was taken in a beaker, Hydrochloric acid was added drop by drop to water. The temperature and pH of the solution was noted. The following graph was obtained. Choose the correct statements related to this activity.
(i) The process of dissolving and acid in water is highly endothermic.
(ii) The pH of the solution increases rapidly in addition of acid
(iii) The pH of the solution decreases rapidly on addition of acid.
(iv)  The pH of tap water was around 7.0
Ans- b) (i) and (iii)

Ques. Out of the given metals the one which needs to be stored used Kerosene is 
Ans- b) R

Ques. Out of the given metals, the metal Q is 
Ans – d) Magnesium

Ques. Metal which forms amphoteric oxides is 
Ans- a) P

Ques. The increasing order of the reactivity of the four metals is : 
Ans- c) S< P< Q< R

Ques. The hemodialyzer has a semi-permeable lining of tubes which help to :
Ans- c) In passing the waste products in the dialyzing solution.

Ques. Which one of the following is not a function of Artificial Kidney?
Ans- c) To reabsorb essential nutrients from the blood. 

Ques. The used dialysing solution is rich in 
Ans- a) Urea and excess salts

Ques. Which part of the nephron in human kidney, servers the function of reabsorption of certain substance?
Ans- c) Tubules

Video solutions for CBSE Class 10 Term 1 exam 2021-22

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