IGCSE Chemistry: Specimen Questions with Answers 61 - 63 of 240

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Question 61

Write in Short

Short Answer▾

Explain the term equilibrium mixture

Explanation

The concept of chemical equilibrium was developed after Berthollet found that some chemical reactions are reversible. For any reaction mixture to exist at equilibrium, the rates of the forward and backward (reverse) reactions are equal.

The syringe contains a sample of the equilibrium mixture. The plunger was pulled back reducing the pressure.

Question 62

Question

MCQ▾

A compound with the formula XF2 has a relative formula mass of 78.

What is element X?

Choices

Choice (4)

a.

Argon

b.

Calcium

c.

Neon

d.

Zirconium

Answer

b.

Explanation

Correct Option is B because have molecular mass so two fluorine have molecular mass and total formula mass is . When then left is and one calcium have molecular mass. So calcium will be correct answer. As shown in the below fluorine atom and one calcium atom form CaF2

Fluorine Atom and One Calcium Atom Form CaF2

Question 63

Question

MCQ▾

Which information about carbon dioxide and methane is correct?

Choices

Choice (4)

a.

Image for Carbon Dioxide and Methane: Choice A

b.

Image for Carbon Dioxide and Methane: Choice B

c.

Image for Carbon Dioxide and Methane: Choice C

d.

Image for Carbon Dioxide and Methane: Choice D

Answer

b.

Explanation

Correct option is B i.e.. greenhouse effect because The greenhouse effect happens when certain gases — known as greenhouse gases — collect in Earth՚s atmosphere. These gases include carbon dioxide , methane, nitrous oxide , fluorinated gases, and ozone. … Animals and plants release carbon dioxide when they respire, or breathe.

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