IGCSE Chemistry: Specimen Questions with Answers 48 - 49 of 240

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Question 48

Question

MCQ▾

The list shows four methods that were suggested for the formation of carbon dioxide.

1 action of an alkali on a carbonate

2 action of heat on a carbonate

3 complete combustion of methane

4 reaction of a carbonate with oxygen

Which methods would result in the production of carbon dioxide?

Choices

Choice (4)

a.

b.

c.

d.

Answer

c.

Explanation

Correct option is C i.e.. and because when alkali act on carbonate then all the carbonates in this Group undergo thermal decomposition to give the metal oxide and carbon dioxide gas. And when there is complete combustion of methane then Combustion of Methane. The reactants are on the left side of the equation and the products are on the right. In the reaction, the bonds in the methane and oxygen come apart, the atoms rearrange and then re-bond to form water and carbon dioxide.

Question 49

Question

MCQ▾

Carbon is unique because ________.

Choices

Choice (4)

a.

It is the most abundant element

b.

It is very reactive

c.

It has a valency of

d.

All of the above

Answer

c.

Explanation

Carbon is unique because it has a valency of and forms covalent bonds, i.e.. shares its electrons other elements or with itself.

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