Chemistry (Part-2) (CDS-Solved Paper)

Total Questions: 50

21. Methyl isocyanate gas, which was involved in the disaster in Bhopal in December, 1984, was used in the Union Carbide Factory for production of [Evening Shift-2016 (II)]

Correct Answer: (d) pesticides
Solution:

Methyl Isocyanate (MIC) gas was used as a precursor for the formation of pesticides in UCIL (Bhopal). The toxic substance made its way into and around the towns located near the plant.

22. ‘German silver’ is used to make decorative articles, coinage metal, ornaments etc. The name is given because [Evening Shift-2016 (II)]

Correct Answer: (c) its appearance is like silver
Solution:

German silver is an alloy of copper, zinc and nickel. It is called so as it appears like silver.

23. Vitamin-B₁₂ deficiency causes pernicious anaemia. Animals cannot synthesise vitamin-B₁₂. Humans must obtain all their vitamin-B₁₂ from their diet. The complexing metal ion in vitamin -B₁₂ is [Evening Shift-2016 (II)]

Correct Answer: (c) Co³⁺ (cobalt ion)
Solution:

Vitamin-B₁₂ is also called as cobalamin and contain Co³⁺ ion. Its deficiency in diet causes pernicious anaemia. It is an autoimmune disorder that can lead to serious complications. It occurs when the body cannot absorb enough vitamin B-12.

24. A piece of ice, 100 g in mass is kept at 0°C. The amount of heat it requires to melt at 0°C is (take latent heat of melting of ice to be 333.6 J/g) [Evening Shift-2016 (II)]

Correct Answer: (c) 33360 J
Solution:

Latent heat is the amount of heat required per unit mass during the change of phase of a substance. SI unit Jkg⁻¹

25. Which one of the following is an example of chemical change? [Evening Shift-2016 (II)]

Correct Answer: (a) Burning of paper
Solution:

Chemical change involves change in chemical composition of matter. During magnetisation of iron, dissolution of sugar in water and preparation of ice from water, the chemical compositions do not alter hence they are physical change. While burning of paper results in formation of carbon dioxide and water vapours, which have new chemical composition, hence it is called chemical change.

26. Which of the following statement(s) is/are correct? [Evening Shift-2016 (II)]

1. Acid rain reacts with buildings made from limestone.
2. Burning of sulphur containing coal can contribute to acid rain.
3. Eutrophication is an effective measure to control pollution.
Select the correct answer using the codes given below.

Correct Answer: (a) 1 and 2
Solution:

Acid rain causes decomposition of limestone.

Hence statement 1, 2 are correct and statements 3 is incorrect

27. Which one of the following statements is not correct? [Evening Shift-2016 (II)]

Correct Answer: (c) Hydrogen has no isotopes
Solution:

Hydrogen has three known isotopes namely protium, deuterium and tritium.

28. Which one of the following statements is not correct? [Evening Shift-2016 (II)]

Correct Answer: (d) All the atoms of an element will always have same number of neutrons
Solution:

Two atoms are said to belongs to an element when they have same number of protons. But they can have different number of neutrons. e.g. the isotopes of an element have same number of protons, but different number of neutrons. Hence statements given option (d) is incorrect.

29. The synthetic rubber has replaced natural rubber for domestic and industrial purposes. Which one of the following is the main reason behind that? [Evening Shift-2016 (II)]

Correct Answer: (c) Raw materials for synthetic rubber are easily available
Solution:

Natural rubber is made from the latex of rubber tree found in the hot, damp forests of South-East Asia, Africa and South America. But during second World War the United States, which essentially needed rubber for its growing industries, was cut off from all sources of natural rubber.

Hence, it developed synthetic rubber plant which is a product of petroleum refining and styrene, to sustain its industries. Thus, easy availability of raw materials from products of petroleum refining industries lead to growth of synthetic rubber.

30. Which of the following statements with regard to Portland cement are correct? [Evening Shift-2015 (II)]

Correct Answer: (d) 1 and 2
Solution:

Functions of ingredients of cement are as follows:
● Silica (SiO₂) It imparts strength to the cement due to the formation of dicalcium and tricalcium silicates.
● Alumina (Al₂O₃) It imparts quick setting property to the cement. It acts as a flux and it lowers the clinkering temperature.
Hence, statement 1 and 2 are correct regaring portiand cement.