IGCSE Chemistry: Specimen Questions with Answers 55 - 57 of 240

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Question 55

Question

MCQ▾

We use the term “relative” vapour density because

Choices

Choice (4)

a.

It is easier to calculate

b.

It is a misnomer

c.

It is basically a measurement with respect to another gas

d.

None of the above

Answer

c.

Explanation

We use the term “relative” vapour density because it is basically a measurement with respect to another gas.

Question 56

Write in Short

Short Answer▾

Dibasic acids can form salts of the type and .

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

Or

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

technique used

Explanation

We should melt the sample of malonic acid at .

Question 57

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Write in Short

Short Answer▾
Describe a simple test-tube reaction which shows the effect of particle size on the rate at which a solid reacts with a solution.

[3 Marks]

Explanation

Action of HCl on solid sodium carbonate.

Take a small quantity of solid sodium carbonate in a test tube. Then add distilled water into it. Cork the test tube with a double bore cork and insert a thistle funnel into the test tube. Then place a beaker containing lime water near the test tube. Then insert one end of the delivery tube into the test tube and the other end into the beaker. Now add HCl into the test tube through the thistle funnel and observe the change in colour of the lime water. For examination use

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