# The percentage of an element $m$ is 53 in its oxide of molecular formula $M_2O_3$.Its atomic mass is about

$(a)\;45\qquad(b)\;9\qquad(c)\;18\qquad(d)\;27$

Let the mass of oxide be 100
$\therefore$ mass of element m is 53
Mass of oxygen is 100-53=47
$\therefore$ Equivalent mass of element =$\large\frac{mass\;of\;element}{mass\;of\;oxygen}$$\times 8 \qquad\qquad\qquad\qquad\qquad\;\;=\large\frac{53}{47}$$\times 8$
$\qquad\qquad\qquad\qquad\qquad\;\;=9$(approx)
$\therefore$ Atomic mass=Equivalent mass$\times$ valency
$\Rightarrow 9\times 3$
$\Rightarrow 27amu$
Hence (d) is the correct answer.