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# A carbon compound containing only carbon and oxygen has an approximate molecular mass of 290.On analysis,it is found to contain 50% by mass of each element .What is the molecular formula of the compound?

$\begin{array}{1 1}(a)\;C_4O_3&(b)\;C_{12}O_9\\(c)\;C_6 O_2&(d)\;CO\end{array}$

The empirical formula $=C_4O_3$
Empirical formula mass =$(4\times 12)+(3\times 16)=96$
Molecular mass =290
$n=\large\frac{Mol.mass}{Emp.mass}=\large\frac{290}{96}$
$\Rightarrow 3$(approx)
Molecular formula=$n\times Empirical\;formula$
$\qquad\qquad\qquad\;=3\times C_4O_3$
$\qquad\qquad\qquad\;= C_{12} O_9$
Hence (b) is the correct option.