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IGCSE Chemistry Extended3.1.2—Molecular formula of a compound as theTopic Practice

3.1.2—Molecular formula of a compound as the

• Define the molecular formula of a compound as the number and type of different atoms in one molecule

Question 7

[Maximum number: 1]

The diagram shows the structure of a molecule of ethyl ethanoate.

Question image

What is the molecular formula of a molecule of ethyl ethanoate?

A

CHO

B

C4H8O2\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}

C

C4(H2)2(O2)\mathrm{C}_{4}\left(\mathrm{H}_{2}\right)_{2}\left(\mathrm{O}_{2}\right)

D

C2H4O\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}

Question 8

[Maximum number: 1]

Caffeine is a stimulant found in coffee.

Question image

caffeine

Which formula represents caffeine?

A

C7H10 N4O2\mathrm{C}_{7} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2}

B

C8H10 N3O2\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{3} \mathrm{O}_{2}

C

C8H10 N4O2\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2}

D

C8H11 N4O2\mathrm{C}_{8} \mathrm{H}_{11} \mathrm{~N}_{4} \mathrm{O}_{2}

Question 8

[Maximum number: 1]

Caffeine is a stimulant found in coffee.

caffeine

caffeine

Which formula represents caffeine?

A

C7H10 N4O2\mathrm{C}_{7} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2}

B

C8H10 N3O2\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{3} \mathrm{O}_{2}

C

C8H10 N4O2\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2}

D

C8H11 N4O2\mathrm{C}_{8} \mathrm{H}_{11} \mathrm{~N}_{4} \mathrm{O}_{2}

Question 9

[Maximum number: 1]

The chemical formulae of two substances, W and X, are given.
W NaAlSi3O8\mathrm{NaAlSi}_{3} \mathrm{O}_{8}
X CaAl2Si2O8\quad \mathrm{CaAl}_{2} \mathrm{Si}_{2} \mathrm{O}_{8}
Which statements are correct?

1 W and X contain the same amount of oxygen.
2 W contains three times as much silicon as X.
3 X contains twice as much aluminium as W.

A

1 and 2

B

1 and 3

C

2 and 3

D

1, 2 and 3

0 selected