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Some Basic Concepts of Chemistry question

2021 · 16 Mar · Shift 1 · Q16
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Some Basic Concepts of Chemistry question

2021 · 16 Mar · Shift 1 · Q16

JEE MainChemistrySome Basic Concepts of ChemistryNumerical+4 / −1
Complete combustion of 750 g of an organic compound provides 420 g of CO2CO_2CO2​ and 210 g of H2OH_2OH2​O. The percentage composition of carbon and hydrogen in organic compound is 15.3 and ‾\underline{\hspace{2cm}}​ respectively. (Round off to the Nearest Integer).
Numerical answer
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Correct answer: 3

  1. Find mass of carbon from CO2CO_2CO2​

Given mass of CO2=420 gCO_2 = 420\,\text{g}CO2​=420g.

In 44 g44\,\text{g}44g of CO2CO_2CO2​, mass of carbon =12 g= 12\,\text{g}=12g.

So, mass of carbon in 420 g420\,\text{g}420g of CO2CO_2CO2​ is

Mass of C=420×1244=114.545 g\text{Mass of C} = 420 \times \frac{12}{44} = 114.545\,\text{g}Mass of C=420×4412​=114.545g
  1. Find percentage of carbon

Mass of organic compound =750 g= 750\,\text{g}=750g.

%C=114.545750×100=15.27%≈15.3%\%\text{C} = \frac{114.545}{750} \times 100 = 15.27\% \approx 15.3\%%C=750114.545​×100=15.27%≈15.3%

This matches the given value.

  1. Find mass of hydrogen from H2OH_2OH2​O

Given mass of H2O=210 gH_2O = 210\,\text{g}H2​O=210g.

In 18 g18\,\text{g}18g of H2OH_2OH2​O, mass of hydrogen =2 g= 2\,\text{g}=2g.

So, mass of hydrogen in 210 g210\,\text{g}210g of H2OH_2OH2​O is

Mass of H=210×218=23.333 g\text{Mass of H} = 210 \times \frac{2}{18} = 23.333\,\text{g}Mass of H=210×182​=23.333g
  1. Find percentage of hydrogen
%H=23.333750×100=3.111%\%\text{H} = \frac{23.333}{750} \times 100 = 3.111\%%H=75023.333​×100=3.111%

Rounded to the nearest integer,

%H≈3\%\text{H} \approx 3%H≈3
  1. Final Answer

The percentage of hydrogen is

3\boxed{3}3​
  1. Comparison with stored correct answer

Stored correct answer = 333.

Our derived answer also is 333, so they agree.

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