Easy MCQ +4 / -1 PYQ · JEE Mains 2022

If a rocket runs on a fuel (C15H30) and liquid oxygen, the weight of oxygen required and CO2 released for every litre of fuel respectively are :

(Given : density of the fuel is 0.756 g/mL)

  1. A 1188 g and 1296 g
  2. B 2376 g and 2592 g
  3. C 2592 g and 2376 g Correct answer
  4. D 3429 g and 3142 g

Solution

<p>C<sub>15</sub>H<sub>30</sub> + ${{45} \over 2}$O<sub>2</sub> $\to$ 15CO<sub>2</sub> + 15H<sub>2</sub>O</p> <p>Given, volume of fuel = 1L = 1000 ml</p> <p>And density of fuel = 0.756 g/ml</p> <p>We know,</p> <p>$d = {w \over v}$</p> <p>$\Rightarrow 0.756 = {w \over {1000}}$</p> <p>$\Rightarrow$ w = 756 gm</p> <p>$\therefore$ weight of fuel = 756 gm</p> <p>Molar mass of C<sub>15</sub>H<sub>30</sub> = 15 $\times$ 12 + 30 = 210</p> <p>$\therefore$ Moles of C<sub>15</sub>H<sub>30</sub> = ${{756} \over {210}}$</p> <p>From equation you can see,</p> <p>1 mole of C<sub>15</sub>H<sub>30</sub> react with ${{45} \over 2}$ mole of O<sub>2</sub></p> <p>$\therefore$ ${{756} \over {210}}$ moles of C<sub>15</sub>H<sub>30</sub> react with ${{45} \over 2} \times {{756} \over {210}}$ moles of O<sub>2</sub></p> <p>$\therefore$ Moles of O<sub>2</sub> required = ${{45} \over 2} \times {{756} \over {210}}$</p> <p>$\therefore$ Mass of O<sub>2</sub> required = ${{45} \over 2} \times {{756} \over {210}}$ $\times$ 32 = 2592 g</p> <p>Also,</p> <p>From 1 mole of C<sub>15</sub>H<sub>30</sub> 15 moles of CO<sub>2</sub> formed</p> <p>$\therefore$ From ${{756} \over {210}}$ moles of C<sub>15</sub>H<sub>30</sub> 15 $\times$ ${{756} \over {210}}$ moles of CO<sub>2</sub> formed</p> <p>$\therefore$ Moles of CO<sub>2</sub> formed = 15 $\times$ ${{756} \over {210}}$</p> <p>$\therefore$ Mass of CO<sub>2</sub> formed = 15 $\times$ ${{756} \over {210}}$ $\times$ 44 = 2376 g</p>

About this question

Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept

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