JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Some Basic Concepts of Chemistry

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Complete combustion of 750 g of an organic compound provides 420 g of CO₂ and 210 g of H₂O. The percentage composition of carbon and hydrogen in organic compound is 15.3 and ____ respectively. (Round off to the nearest Integer).

Answer: 3

Solution

Complete combustion sends every carbon atom of the compound into

C O_{2}

and every hydrogen atom into

H_{2} O

, so the masses of the two elements follow from the molar masses of those products:

m_{C} = 420 \times \frac{12}{44} = 114.5 g, m_{H} = 210 \times \frac{2}{18} = 23.33 g

Expressed as fractions of the 750 g burnt,

% C = \frac{114.5}{750} \times 100 = 15.3, % H = \frac{23.33}{750} \times 100 = 3.11

Rounded to the nearest integer, the percentage of hydrogen in the compound is 3.

JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Integer answer

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JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Some Basic Concepts of Chemistry

Solution

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