IGCSE Chemistry: Specimen Questions with Answers 127 - 130 of 240

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Question 127

Question

MCQ▾

Lanthanides and actinides are ________ in nature.

Choices

Choice (4)

a.

Non metallic

b.

Metallic

c.

None of the above

d.

Question does not provide sufficient data or is vague

Answer

b.

Explanation

Lanthanides and Actinides are metallic in nature.

Question 128

Question

MCQ▾

1 mole of any gaseous substance occupies ________ litres at S. T. P.

Choices

Choice (4)

a.

22.4

b.

c.

Question does not provide sufficient data or is vague

d.

All of the above

Answer

a.

Explanation

  • Molar volume of a gas is the volume occupied by 1 mole of gas at the standard temperature and pressure (S. T. P.) . One mole of a gas occupies litres or at S. T. P.
  • S. T. P means standard temperature and pressure. At S. T. P. , the value of temperature is or and that of pressure is of Hg or .
  • Thus one mole of any substance occupies litres at standard temperature and pressure.

Question 129

Question

MCQ▾

What depletes Ozone layers?

Choices

Choice (4)

a.

b.

Carbon Dioxide

c.

d.

All a., b. and c. are correct

Answer

d.

Explanation

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

Question 130

Edit

Write in Short

Short Answer▾
    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.

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