SECTION A (Multiple Choice Questions - 1 Mark Each)
Q1. In the following experimental setup of electrolysis of water, if P and Q are the gases collected in the test tubes enclosing the electrodes R and S, then select the option/options in which the matching is correct:
(i) P - Oxygen gas, R - Anode
(ii) P - Hydrogen gas, R - Cathode
(iii) Q - Hydrogen gas, S - Cathode
(iv) Q - Oxygen gas, S - Anode
(a) (i) and (ii) (b) (iii) and (iv) (c) (i) and (iii) (d) (ii) and (iv)
Answer: (d) (ii) and (iv)
Explanation: During the electrolysis of water, hydrogen gas is collected at the cathode and oxygen gas at the anode. P (hydrogen at cathode) and Q (oxygen at anode) matches (ii) and (iv).
Q2. You have three aqueous solutions A, B and C as given below:
A: Potassium nitrate, B: Ammonium chloride, C: Sodium carbonate.
The ascending order of the pH of these solutions is:
(a) A < B < C (b) B < C < A (c) C < A < B (d) B < A < C
Answer: (d) B < A < C
Explanation: Ammonium chloride (B) is acidic (pH < 7), potassium nitrate (A) is neutral (pH = 7), and sodium carbonate (C) is basic (pH > 7). Thus, ascending order of pH is B < A < C.
Q3. Select from the following a statement which is not true about burning of magnesium ribbon in air:
(a) It burns with a dazzling white flame.
(b) A white powder is formed on burning.
(c) It is an endothermic reaction.
(d) It is an example of a combination reaction.
Answer: (c) It is an endothermic reaction.
Explanation: Burning of magnesium is an exothermic reaction as it releases heat and light.
Q4. A hydrocarbon which does not belong to the same homologous series of carbon compounds is:
(a) C_4H_{10} (b) C_6H_{14} (c) C_7H_{14} (d) C_{10}H_{22}
Answer: (c) C_7H_{14}
Explanation: C_4H_{10}, C_6H_{14}, and C_{10}H_{22} are alkanes (C_nH_{2n+2}), whereas C_7H_{14} is an alkene (C_nH_{2n}).
Q5. The colour of the solution observed after about 1 hour of placing iron nails in copper sulphate solution is:
(a) Blue (b) Pale green (c) Yellow (d) Reddish brown
Answer: (b) Pale green
Explanation: Iron displaces copper from copper sulphate to form ferrous sulphate (FeSO_4), which is pale green.
Q6. Juice of tamarind turns blue litmus to red. It is because of the presence of a chemical compound called:
(a) Acetic acid (b) Methanoic acid (c) Oxalic acid (d) Tartaric acid
Answer: (d) Tartaric acid
Explanation: Tamarind naturally contains tartaric acid.
Q7. The water of crystallisation is present in:
(i) Bleaching Powder (ii) Plaster of Paris (iii) Washing Soda (iv) Baking Soda
(a) (ii) and (iv) (b) (ii) and (iii) (c) (i) and (iii) (d) (i) and (iv)
Answer: (b) (ii) and (iii)
Explanation: Plaster of Paris (CaSO_4 \cdot \frac{1}{2}H_2O) and Washing Soda (Na_2CO_3 \cdot 10H_2O) contain water of crystallisation.
Q8. A tall pea plant with round seeds (TTRR) is crossed with a short pea plant with wrinkled seeds (ttrr). The F_1 generation will be:
(a) 25% tall with round seeds
(b) 50% tall with wrinkled seeds
(c) 75% tall with wrinkled seeds
(d) 100% tall with round seeds
Answer: (d) 100% tall with round seeds
Explanation: F_1 generation offspring are dihybrids (TtRr), exhibiting dominant tall and round traits entirely.
Q9. A pair of endocrine glands located in the human brain is:
(a) Parathyroid and Pituitary (b) Pineal and Thymus
(c) Hypothalamus and Thymus (d) Hypothalamus and Pineal
Answer: (d) Hypothalamus and Pineal
Explanation: Both hypothalamus and pineal glands are situated within the brain.
Q10. Select the option having correct matching of the organism given in Column I with the mode of reproduction in Column II:
P. Leishmania - 1. Regeneration
Q. Spirogyra - 2. Multiple Fission
R. Planaria - 3. Binary Fission
S. Plasmodium - 4. Fragmentation
(a) P-4, Q-2, R-1, S-3 (b) P-3, Q-4, R-5, S-2
(c) P-3, Q-4, R-1, S-2 (d) P-4, Q-3, R-2, S-1
Answer: (c) P-3, Q-4, R-1, S-2
Explanation: Leishmania undergoes binary fission (3), Spirogyra undergoes fragmentation (4), Planaria shows regeneration (1), and Plasmodium undergoes multiple fission (2).
Q11. The basic filtration unit of the excretory system in human beings is:
(a) Nephron (b) Urethra (c) Neuron (d) Urinary bladder
Answer: (a) Nephron
Explanation: Nephrons are the functional filtration units of kidneys.
Q12. In human alimentary canal, the digestive juice secreted by the gastric glands are:
(a) Bile, Trypsin, Pepsin
(b) Hydrochloric acid, Pepsin, Mucus
(c) Lipase, Bile, Mucus
(d) Salivary amylase, Pepsin, Bile
Answer: (b) Hydrochloric acid, Pepsin, Mucus
Explanation: Gastric glands secrete HCl, pepsin, and mucus.
Q13. Identify from the following the ray diagram which shows the correct path of the reflected ray for the ray incident on a concave mirror...
Answer: (c)
Explanation: A ray parallel to the principal axis passes through the principal focus after reflection from a concave mirror.
Q14. The part of human eye which controls the amount of light entering into it:
(a) Iris (b) Cornea (c) Ciliary muscles (d) Pupil
Answer: (d) Pupil
Explanation: The pupil regulates the amount of light entering the eye (aided by the iris).
Q15. Consider the following food chain: Grass → Grasshopper → Frog → Snake → Eagle. If energy at third trophic level is 50 kJ, available energy at producer level was:
(a) 0.5 kJ (b) 5 kJ (c) 500 kJ (d) 5000 kJ
Answer: (d) 5000 kJ
Explanation: Applying the 10% law: Frog (3rd level) = 50 kJ \rightarrow Grasshopper (2nd level) = 500 kJ \rightarrow Grass (Producer) = 5000 kJ.
Q16. The incorrect statement about ozone is:
(a) It is a deadly poisonous gas.
(b) It shields the surface of the earth from UV radiation from sun.
(c) It is used as a refrigerant and in fire-extinguishers.
(d) It is formed by combining oxygen molecule with free oxygen atom.
Answer: (c) It is used as a refrigerant and in fire-extinguishers.
Explanation: Ozone is not used as a refrigerant (CFCs were used, which deplete ozone).
Q17. Assertion (A): Carbon and its compounds are our major sources of fuels.
Reason (R): Most of the carbon compounds on burning release a large amount of heat and light.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
Explanation: Carbon compounds burn in air to release abundant heat and energy, making them ideal fuels.
Q18. Assertion (A): Xylem tissue moves water and minerals obtained from the soil by the roots.
Reason (R): Xylem tissue is found only in the roots of a plant.
Answer: (c) Assertion (A) is true, but Reason (R) is false.
Explanation: Xylem tissue is present throughout the plant (roots, stems, and leaves).
Q19. Assertion (A): In common domestic circuits the earth wire is connected to a metallic plate buried deep inside the earth.
Reason (R): Earth wire ensures any leakage of current keeps potential to that of earth, preventing severe electric shock.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
Explanation: Grounding via earth wire diverts leakage current safely into the earth.
Q20. Assertion (A): Food web is a network of several food chains operating in an ecosystem.
Reason (R): Food web decreases the stability of an ecosystem.
Answer: (c) Assertion (A) is true, but Reason (R) is false.
Explanation: Food webs actually increase the stability and resilience of an ecosystem.
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