IGCSE Chemistry Paper-1: Specimen Questions with Answers 58 - 60 of 99

Question number: 58

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Question

Which of the following is a type of decomposition reaction:

Choices

Choice (4)Response

a.

Displacement

b.

Thermal

c.

Electric

d.

All of the above

Answer

b.

Explanation

The reaction in which heat energy is given to the substance and substance breaks into two or more simpler substances is called thermal decomposition reaction.

Question number: 59

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Question

Which of the following group is of ketone?

Choices

Choice (4)Response

a.

–OH

b.

–CHO

c.

–COOH

d.

–CO

Answer

d.

Explanation

Ketones are organic compounds which incorporate a carbonyl functional group, C = O. The carbon atom of this group has two remaining bonds that may be occupied by hydrogen or alkyl or aryl substituents. Ketone group always occur in the middle of a carbon chain thus a ketone should consist of atleast three carbon atoms in its compound.

Question number: 60

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Question

Calcium oxide reacts with water to form slaked lime. What type of reaction is this?

Formation of slaked lime

Formation of Slaked Lime

Choices

Choice (4)Response

a.

Oxidation reaction

b.

Displacement reaction

c.

Reduction reaction

d.

Combination reaction

Answer

d.

Explanation

The chemical reaction follow is:

CaO (s) (Quick Lime) + H2O (l) → Ca (OH) 2 (aq) (Slaked lime) ‎

Reactions in which two or more substances combine together to form a single compound are called combination reaction.

Here, Calcium hydroxide is formed by the combination of quick lime and water. Therefore is a combination reaction.

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