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5mL of a gas containing only carbon and hydrogen were mixed with an excess of oxygen (30mL) and the mixture exploded by means of an electric spark. After the explosion, the volume of the mixed gases remaining was 25mL. On adding a concentrated solution of potassium hydroxide, the volume further diminished to 15mL, the residual gas being pure oxygen. All volumes have been reduced to NTP. Calculate the molecular formula of the hydrocarbon gas.

Answer» <html><body><p></p>Solution :Let the <a href="https://interviewquestions.tuteehub.com/tag/formula-464310" style="font-weight:bold;" target="_blank" title="Click to know more about FORMULA">FORMULA</a> of the hydrocarbonbe `C_(x)H_(y)`. Its <a href="https://interviewquestions.tuteehub.com/tag/combustion-13975" style="font-weight:bold;" target="_blank" title="Click to know more about COMBUSTION">COMBUSTION</a> can be shows by the following equation: <br/> `{:(C_(x)H_(y)+,(x+(y)/(<a href="https://interviewquestions.tuteehub.com/tag/4-311707" style="font-weight:bold;" target="_blank" title="Click to know more about 4">4</a>))O_(2)rarr,xCO_(2)+(y)/(2)H_(2)O),(1vol,(x+(y)/(4))mL,xvol),(5mL,5(x+(y)/(4))mL,5xvol):}` <br/> Volume of carbon dioxide produced `= (25 - 15) = 10mL` <br/> `5x = 10` <br/> or `x = 2` <br/> Volume of oxygen used `= (30 - 15) = 15mL` <br/> `5[x+(y)/(4)] = 15` or `x +(y)/(4) = (15)/(5) = <a href="https://interviewquestions.tuteehub.com/tag/3-301577" style="font-weight:bold;" target="_blank" title="Click to know more about 3">3</a>` <br/> or `2 +(y)/(4) = 3` <br/> or `(y)/(4) = 3 - 2 = 1` <br/> or `y = 4` <br/> <a href="https://interviewquestions.tuteehub.com/tag/thus-2307358" style="font-weight:bold;" target="_blank" title="Click to know more about THUS">THUS</a>, the molecular formula of the hydrocarbon `= C_(2)H_(4)`</body></html>


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