Friday, April 26, 2019

WBCS Polity and Constitution MCQs Prelims and Mains

Quiz on General Science (Chemistry) For WBCS Prelims Exams P3

21. Which of the following is a neutral oxide
(A) Calcium oxide
(B) Sulphur-di-Oxide
(C) Nitric oxide
(D) Zinc oxide
Correct Answer: [D] Zinc oxide.

22. Which of the following mixtures can be separated by using separating funnel?
(A) Water + oil
(B) Petrol + kerosene
(C) Water + sugar
(D) Water + milk
Correct Answer: [A] Water + oil.

23. Mg2+ is isoelectronic with
(A) Zn2+
(B) Cu+
(C) Ca2+

(D) Na+
Correct Answer: [D] Na+ .

24. The half-life of a substance is 10 days. How much of the substance will be left after 40 days if the initial mass is 2 gm
(A) 0.0125 gm
(B) 1.25 gm
(C) 0.125 gm
(D) 5 gm
Correct Answer: [C] 0.125 gm.

25. Brass is an alloy of
(A) Copper and Aluminium
(B) Copper and Zinc
(C) Iron and Copper
(D) Copper and Tin
Correct Answer: [B] Copper and Zinc.

26. Which of the following property is common in Graphite a Diamond ?
(A) Crystal structure
(B) Density
(C) Electrical conductivity
(D) Relative atomic weight
Correct Answer: [B] Density.

27. In the manufacture of steel by open-hearth process cast iron used has no phosphorus but has manganese as an impurity. The furnace should have a lining of
(A) silica
(B) lime or magnesia
(C) magnesia
(D) lime
Correct Answer: [A] silica.

28. An alloy contains 20% zinc, 45% nickel and rests aluminum. The total mass in gm of the alloy containing 105 gm of aluminum is
(A) 250
(B) 300
(C) 170
(D) 200
Correct Answer: [B] 300.

29. A pair of compounds which cannot exist together in solution is
(A) Sodium bicarbonate and sodium carbonate
(B) Sodium carbonate and sodium soda
(C) Sodium bicarbonate and caustic soda
(D) Sodium bicarbonate and water
Correct Answer: [C] Sodium bicarbonate and caustic soda.

30. How many gms of a dibasic acid (mol wt 200) should be present in 100 ml of its aqueous solution to give 0.1 (N) strength?
(A) 10gm
(B) 20 gm
(C) 2 gm
(D) 1 gm
Correct Answer: [D] 1 gm.


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