2.00g of a carbon compound is burnt in excess oxygen.4.77g of carbon dioxide is produced.What percentage (to the nearest 1%) of carbon is in the original compound?

A 21%
B 26%
C 42%
D 52%
E 65%

Answer:

10) E

Mass of CO₂ produced = 4.77 g

Mr of CO₂ = 12 + 16 + 16 = 44
Moles = Mass ÷ Mr = 4.77 ÷ 44 ≈ 0.1

Molar ratio of (C : CO₂) = 1 : 1
Moles of C = 0.1 mol

Mass of C = 0.1 x 12 = 1.2 g

Percentage = (1.2 / 2) x 100 = 60%

This is closest to 65% which is option E.