General science

14 chapters 16 solved questions

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What is the pH of pure water at 25\(^\circ\)C? Answer: D. 7 Answer: (D) 7 Pure water is neutral; at 25°C its pH is 7. Below 7 is acidic and above 7 is basic. Acids, bases and salts 1 answer
Which blood components help in the clotting of blood? Answer: B. Platelets Answer: (B) Platelets Platelets (thrombocytes) gather at a wound and release factors that start clotting. RBCs carry ox... Human body systems 1 answer
Which type of lens is used to correct myopia (short-sightedness)? Answer: C. Concave lens Answer: (C) Concave lens In myopia the image forms in front of the retina. A concave (diverging) lens moves it back... Light 1 answer
The loss of water in the form of vapour through the stomata of leaves is called: Answer: A. Transpiration Answer: (A) Transpiration Transpiration is the loss of water vapour mainly through stomata. Guttation is the loss o... Plants and heredity 1 answer
What is the chemical formula of Plaster of Paris? Answer: D. CaSO ₄ ·½H ₂ O Answer: (D) CaSO ₄ ·½H ₂ O Plaster of Paris is calcium sulphate hemihydrate, CaSO ₄ ·½H ₂ O, made by heating gypsu... Acids, bases and salts 1 answer
What is the SI unit of electric current? Answer: B. Ampere Answer: (B) Ampere Electric current is measured in amperes (A), one of the seven SI base units. Volt is the unit of potent... Electricity and magnetism 1 answer
Which part of the human brain maintains balance and posture of the body? Answer: B. Cerebellum Answer: (B) Cerebellum The cerebellum (hindbrain) coordinates voluntary movements and maintains posture and balance. T... Human body systems 1 answer
Which type of mirror is used as a rear-view mirror in vehicles? Answer: A. Convex mirror Answer: (A) Convex mirror A convex mirror always forms an erect, diminished image and gives a wider field of view,... Light 1 answer
Deficiency of iodine in the diet causes which disease? Answer: C. Goitre Answer: (C) Goitre Iodine is needed to make the thyroid hormone thyroxine; its lack causes goitre (swelling of the thyroid... Nutrition and diseases 1 answer
Insulin is produced by which organ of the human body? Answer: D. Pancreas Answer: (D) Pancreas Insulin is made by the beta cells of the islets of Langerhans in the pancreas and lowers blood suga... Human body systems 1 answer
Night blindness is caused by the deficiency of which vitamin? Answer: C. Vitamin A Answer: (C) Vitamin A Vitamin A is needed to make rhodopsin in the retina; its deficiency causes night blindness. Nutrition and diseases 1 answer
Which of the following is the hardest natural substance? Answer: B. Diamond Answer: (B) Diamond Diamond, an allotrope of carbon in which each atom is bonded to four others, is the hardest natural s... Carbon and its compounds 1 answer
What is the chemical formula of baking soda? Answer: D. NaHCO3 Answer: (D) NaHCO₃ Baking soda is sodium hydrogen carbonate, NaHCO₃. Na₂CO₃ is washing soda (in its hydrated form). Acids, bases and salts 1 answer
Which gas is commonly known as 'laughing gas'? Answer: A. Nitrous oxide Answer: (A) Nitrous oxide Nitrous oxide (N₂O) is called laughing gas and is used as a mild anaesthetic. Atoms and the periodic table 1 answer
What is the SI unit of electrical resistance? Answer: A. Ohm Answer: (A) Ohm Resistance is measured in ohms (Ω). By Ohm's law, R = V/I. Electricity and magnetism 1 answer
Scurvy is caused by the deficiency of which vitamin? Answer: A. Vitamin C Answer: (A) Vitamin C Lack of vitamin C (ascorbic acid) causes scurvy, with bleeding gums. Vitamin D deficiency causes... Nutrition and diseases 1 answer