CIE Chemistry Paper-1: Specimen Questions 59 - 61 of 99

Question number: 59

MCQ▾

Question

Which of the following group is of ketone?

Choices

Choice (4) Response
a.

–COOH

b.

–CO

c.

–CHO

d.

–OH

Answer

b.

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

MCQ▾

Question

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

Formation of slaked lime

Formation of slaked lime

Calcium oxide reacts with water to form slaked lime

Choices

Choice (4) Response
a.

Displacement reaction

b.

Reduction reaction

c.

Oxidation 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.

Question number: 61

MCQ▾

Question

Which of the following allotrope of carbon is more reactive?

Choices

Choice (4) Response
a.

A and B of them are non reactive.

b.

Graphite

c.

Diamond

d.

A and B of them are equally reactive

Answer

b.

Explanation

In diamond, all the four valencies of each carbon atom are satisfied by bonding to other carbon atoms through regular covalent bonds. The electrons are held tightly between the nuclei, and there are no mobile electrons. Thus diamond structure is a closely packed structure and is extremely unreactive at room temperature.

In graphite, carbon atoms in each layer are bonded to three carbon atoms. This gives some double-bond character to C-C bonds giving it the presence of delocalized p-electron system. The layer-to-layer large distance makes graphite to have an open structure and so it reacts more readily.

 Structure of Graphite

Structure of Graphite

Arrangement of carbon to form graphite in the diagram

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