CIE Chemistry (US-0439): Specimen Questions with Answers 129 - 132 of 240

Question number: 129

MCQ▾

Question

What depletes Ozone layers?

Choices

Choice (4) Response

a.

b.

c.

Carbon Dioxide

d.

All a. , b. and c. are correct

Answer

d.

Explanation

Green house gases like , , and carbon dioxide depletes ozone layers.

Question number: 130

Short Answer Question▾

Write in Short

    1. Sulfuric acid and malonic acid are both dibasic acids. One mole of a dibasic acid can form two moles of hydrogen ions.

    H2SO4 → 2H+ + SO42–

    Dibasic acids can form salts of the type Na2X and CaX.

  1. Malonic acid is a white crystalline solid which is soluble in water. It melts at 135 °C. The structural formula of malonic acid is given below. It forms salts called malonates.

CH2 (COOH) 2 or HOOC – CH2 – COOH

  1. How could you determine if a sample of malonic acid is pure?

technique used

Explanation

We should melt the sample of malonic acid at 132 - 135 °C.

Question number: 131

Short Answer Question▾

Write in Short

State the name given to a chemical reaction which releases energy.

…………………………………………………………………………………………………………….

Explanation

as complete combustion of fossil fuel named as octane.

Question number: 132

Short Answer Question▾

Write in Short

Aluminum and gallium are in Group III of the Periodic Table.

  • When it is a gas, gallium (III) chloride has the structure shown below.

gas, gallium(III) chloride structure

Gas, Gallium (III) Chloride Structure

gas, gallium (III) chloride structure

Write the molecular formula for gallium (III) chloride.

……………………………………………………………………………………………………………………. [1]

Explanation

Gallium chloride molecular if GaCl3 and its reaction is given below. It can also prepared by