Chemistry (Part-3) (CDS-Solved Paper)

Total Questions: 18

11. Which of the following solutions will not change the colour of blue litmus paper to red? [Morning Shift-2014 (I)]

1. Acid solution
2. Base solution
3. Common salt solution
Select the correct answer using the codes given below.

Correct Answer: (b) 2 and 3
Solution:

The litmus paper turns red in acidic solution and blue in basic solution. The neutral solution does not affect the litmus paper. Thus, only acidic solution can change the colour of blue litmus paper to red.

12. Nitric oxide pollution can lead to all of the following, except [Morning Shift-2014 (I)]

Correct Answer: (d) silicosis in human
Solution:

Silicosis in human is a lung disease which occurs due to inhalation of silica-dust.

13. Addition of ethylene dibromide to petrol [Morning Shift-2014 (I)]

Correct Answer: (d) serves as a substitute of tetraethyl lead
Solution:

Ethylene dibromide is added to petrol in place of tetraethyl lead to save the environment from lead pollution.

14. Read the following statements carefully and choose the correct option. [Morning Shift-2014 (I)]

Statement I Clay layers are poor aquifers.
Statement II The inter-particle space of clay minerals is the least.
Codes

Correct Answer: (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
Solution:

An aquifer is an underground layer of water bearing rocks. Water bearing rocks are permeable, i.e. they have opening that liquids allows and gases to pass through. But clay layers are poor aquifers.
Clay minerals are dense, impermeable material and act as an ‘aquiteral’, i.e. a layer of material that is almost impenetrable to water. Through groundwater might more through such material, it will do so very slowly.

15. Which of the following are the two main constituents of granite? [Morning Shift-2014 (I)]

Correct Answer: (c) Silica and aluminium
Solution:

Silica and aluminium are the two main constituents of granite. Granite contains 72.04% of silica and 14.42% of aluminium in the form of (Al₂O₃).

16. A metal screw top on a glass bottle, which appears to be stuck could be opened by using the fact that [Morning Shift-2014 (I)]

Correct Answer: (a) the metal expands more than the glass when both are heated
Solution:

Both metal and glass expand when heated. Glass being a non-metal does not have free electrons and hence, have poor thermal conductivity. Thermal conductivity of metals is very high. Therefore, metal expands more than non-metals due to temperature change.

17. Iron sheet kept in moist air covered with rust. Rust is [Morning Shift-2014 (I)]

Correct Answer: (b) a compound
Solution:

Iron forms hydrated iron oxide (rust) when kept open in moist air.

18. Which one of the following gases is supporter of combustion? [Morning Shift-2014 (I)]

Correct Answer: (d) Oxygen
Solution:

Combustion is supported by oxygen because combustion is an oxidation process and this cannot occur without the presence of oxygen, but oxygen is not combustible. So, oxygen is a key reactant in the process of combustion.