Allahabad High Court Recruitment 2023 for Law Clerk Posts, Apply Online at allahabadhighcourt.in
[ad_1] Allahabad High Court Recruitment 2023: High Court of Judicature at Allahabad is looking to…
CBSE Class 10 Science Answer Key 2024 PDF All Sets
[ad_1]
CBSE Class 10 Science Answer Key 2024
Section A
Select and write the most appropriate option out of the four options given for each of the questions 1-20. There is no negative mark for the incorrect response.
1. When 2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as:
(a) NaOH + Zn → NaZnO2 + H20
(b) 2NaOH + Zn → Na2ZnO2 + H2
(c) 2NaOH + Zn → NaZnO2 + H2
(d) 2NaOH + Zn → Na2ZnO2 + H2O
Answer: (b) 2NaOH + Zn → Na2ZnO2 + H2
2. Select from the following a decomposition reaction in which source of energy for decomposition is light:
(a) 2FeSO4 → Fe203+ SO2+ SO3
(b) 2H2O → 2H2+ O2
(c) 2AgBr → 2Ag + Br2
(d) CaCO3 → CaO + CO2
Answer: (c) 2AgBr → 2Ag + Br2
3. A metal and a non-metal that exists in liquid state at the room temperature are respectively :
(a) Bromine and Mercury
(b) Mercury and lodine
(c) Mercury and Bromine
(d) Iodine and Mercury
Answer: (c) Mercury and Bromine
4. Carbon compounds:
(i) are good conductors of electricity.
(ii) are bad conductors of electricity.
(iii) have strong forces of attraction between their molecules.
(iv) have weak forces of attraction between their molecules.
The correct statements are:
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (i) and (iii)
Answer: (d) (i) and (iii)
5. Consider the following compounds :
FeSO4; CuSO4; CaSO4; Na2CO3
The compound having maximum number of water of crystallisation in its crystalline form in one molecule is :
(a) FeSO4
(b) CuSO4
(c) CaSO4
(d) Na2CO3
Answer: (d) Na2CO3 ; 10 water molecules
6. Oxides of aluminium and zine are :
(a) acidic
(b) basic
(c) amphoteric
(d) neutral
Answer: (c) amphoteric; behave as both acidic and basic oxides
7. MnO2 + 4HCI → MnCl2 + 2H2O + Cl2
The reaction given above is a redox reaction because in this case
(a) MnO2 is oxidised and HCI is reduced.
(b) HCI is oxidised.
(c) MnO2 is reduced.
(d) MnO2 is reduced and HCI is oxidised.
Answer: (d) MnO2 is reduced and HCI is oxidised; MnO2 loses its oxygen to form MnCl2 and HCl loses its H to form Cl2.
8. Consider the following statements
(i) The sex of a child is determined by what it inherits from the mother.
(ii) The sex of a child is determined by what it inherits from the father.
(iii) The probability of having a male child is more than that of a female child.
(iv) The sex of a child is determined at the time of fertilisation when male and female gametes fuse to form a zygote.
The correct statements are :
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (iii) and (iv)
(d) i), (iii) and (iv)
Answer: (b) (ii) and (iv)
9. Chromosomes :
(i) carry hereditary information from parents to the next generation.
(ii) are thread like structures located inside the nucleus of an animal cell.
(iii) always exist in pairs in human reproductive cells.
(iv) are involved in the process of cell division.
The correct statements are :
(a) (i) and (ii)
(b) (iii) and (iv)
(a) (i), (ii) and (iv)
(d) (i) and (iv)
Answer: (a) (i) and (ii)
10. In a nerve cell, the site where the electrical impulse is converted into a chemical signal is known as :
(a) Axon
(b) Dendrites
(c) Neuromuscular junction
(d) Cell body
Answer: (c) Neuromuscular junction; a neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber.
11. A stomata closes when:
(i) it needs carbon dioxide for photosynthesis.
(ii) it does not need carbon dioxide for photosynthesis.
(iii) water flows out of the guard cells.
(iv) water flows into the guard cells.
The correct reason(s) in this process is/are :
(a) (i) only
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)
Answer: (c) (ii) and (iii);
Plant closes stomata when it does not need carbon dioxide for photosynthesis to prevent water loss.
When water exits from the guard cells, they become flaccid. This results in closing of stomata.
12. At what distance from a convex lens should an object be placed to get an image of the same size as that of the object on a screen?
(a) Beyond twice the focal length of the lens.
(b) At the principal focus of the lens.
(c) At twice the focal length of the lens.
(d) Between the optical centre of the lens and its principal focus.
Answer: (c) At twice the focal length of the lens;
Here the real image is formed at the other centre of curvature. The size of the image is the same as compared to that of the object.
13. The lens system of human eye forms an image on a light sensitive screen, which is called as:
(a) Cornea
(b) Ciliary muscles
(c) Optic nerves
(d) Retina
Answer: (d) Retina
14. The pattern of the magnetic field produced inside a current carrying solenoid is:
Answer: (a); The field lines inside the solenoid are in the form of parallel straight lines.
15. Identify the food chain in which the organisms of the second trophic level are missing :
(a) Grass, goat, lion
(b) Zooplankton, Phytoplankton, small fish, large fish
(c) Tiger, grass, snake, frog
(d) Grasshopper, grass, snake, frog, eagle
Answer:
16. In which of the following organisms, multiple fission is a means of asexual reproduction?
(a) Yeast
(b) Leishmania
(c) Paramoecium
(d) Plasmodium
Answer:
(d) Plasmodium
For Q. Nos. 17 to 20, two statements are given – One labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.
17. Assertion (A): Hydrogen gas is not evolved when zinc reacts with nitric acid.
Reason (R): Nitric acid oxidises the hydrogen gas produced to water and itself gets reduced.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
Explanation: Hydrogen gas is not evolved when a metal reacts with nitric acid. This is because HNO3 is a strong oxidising agent. It oxidises H2, produces water and itself gets reduced to nitrogen oxide.
18. Assertion (A): Accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain.
Reason (R): Harmful chemicals are sprayed on the crops to protect them from diseases and pests.
Answer: (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
Explanation: Harmful chemicals may enter an ecosystem and accumulate in the bodies of organisms at the bottom of the food chain, such as plants or small herbivores. As these contaminated organisms are consumed by higher trophic levels, the concentration of pollutants increases. This is because organisms at higher trophic levels eat multiple individuals from the lower trophic levels, magnifying the amount of the substance in their bodies.
19. Assertion (A): The rate of breathing in aquatic organisms is much faster than in terrestrial organisms.
Reason (R): The amount of oxygen dissolved in water is very high as compared to the amount of oxygen in air.
Answer: (c) Assertion (A) is true, but Reason (R) is false.
Explanation: The rate of breathing in aquatic organisms is much faster than in terrestrial organisms because the amount of dissolved oxygen is fairly lower in water than in air and aquatic organisms like fishes obtain oxygen from water present in the dissolved state.
20. Assertion (A): The rainbow is a natural spectrum of sunlight in the sky.
Reason (R): Rainbow is formed in the sky when the sun is overhead and water droplets are also present in air.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
Explanation: As the rainbow is formed naturally by the reflection of sunlight inside the raindrops, it is called a natural spectrum appearing in the sky.
Keep refreshing this page for more answers.
Also Check:
CBSE Class 10 Syllabus 2023-2024 (All Subjects)
CBSE Class 10 Deleted Topics 2023-2024 (All Subjects)
CBSE Class 10 Sample Paper 2023-2024 (All Subjects)
[ad_2]
Source link