Some Basic Concepts Of Chemistry Question 47

Question: Complete combustion of $ 0.858g $ of compound X gives 2.64 g of $ CO _2 $ and 1.26g of $ H _2O $ . The lowest molecular mass X can have:

Options:

A) 43 g

B) 86 g

C) 129 g

D) 172 g

Show Answer

Answer:

Correct Answer: A

Solution:

[a] Moles of $ C={}^{n}CO _2=\frac{2.64}{44}=0.06 $
$ \Rightarrow $ mass of C= 0.72 Mole of $ H=2\times Moles $ of $ H _2O= $ $ 2\times \frac{1.26}{18}=0.14\Rightarrow $ mass of $ H=0.14 $ Compound does not contains oxygen. So $ EF\to {C _{0.06}}{H _{0.14}}\Rightarrow C _3H _{17} $
$ \Rightarrow $ Lowest M.M. = 43



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