CIE Chemistry (US-0439): Specimen Questions with Answers 76 - 77 of 240

Question number: 76

MCQ▾

Question

Carbon forms ________ bond with hydrogen.

Choices

Choice (4) Response

a.

Covalent

b.

Ionic

c.

None of the above

d.

All of the above

Answer

a.

Explanation

  • Carbon forms covalent bond with hydrogen. Carbon has 6 electrons. So its electronic configuration is . Thus it has electrons in its outermost shell. So carbon has valence electrons. To complete its octet carbon has to either gain electrons or lose electrons.

  • But it requires lot of energy in both the processes. So it shares its electrons. Due to presence of valence electrons carbon makes covalent bond by sharing its valence electrons with other atoms.

  • Hydrogen has 1 electron. To complete its duplet configuration it needs 1 electron. So both carbon & hydrogen share their electrons to attain their stable configurations. Thus carbon forms covalent bond with hydrogen.

  • For example in methane, each carbon atom shares its electrons with 4 hydrogen atom.

Image of the structure of ch4

Image of the Structure of ch4

Image of the structure of ch4

Question number: 77

MCQ▾

Question

Calculate the amount of potassium nitrite formed by thermal decomposition of of potassium nitrate.

The chemical reaction taking place is:

[Relative atomic masses: ]

[Give your answer correct to two decimal places]

Choices

Choice (4) Response

a.

11.75

b.

14.75

c.

12.75

d.

13.75

Answer

c.

Explanation

The chemical reaction taking place is:

RMM of each species in this reaction: