CIE Chemistry (US-0439): Specimen Questions with Answers 48 - 50 of 240

Question number: 48

MCQ▾

Question

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) Response

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 number: 49

MCQ▾

Question

Carbon is unique because ________.

Choices

Choice (4) Response

a.

It is very reactive

b.

It has a valency of

c.

It is the most abundant element

d.

Question does not provide sufficient data or is vague

Answer

b.

Explanation

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

Question number: 50

MCQ▾

Question

Group I metals are also known as the Alkali Metals.

Which statement about the metals in Group I is not correct?

Choices

Choice (4) Response

a.

In their reactions they lose electrons

b.

Their atoms all have one electron in their outer shell.

c.

They form ions in their reactions with nonmetals.

d.

They form covalent compounds by sharing electrons.

Answer

d.

Explanation

Correct option is D because alkali metal never forms covalent compound by sharing electrons because alkali metal always donate electron to form + ve ion. In the outer shell of alkali metals it have one electrons. As shown in figure.

Image of Alkali Metals

Image of Alkali Metals

Image of Alkali Metals