Molecular mass of $Ca(OH{)}_2$ is :

The correct option is C $74$
Molecular mass of $Ca(OH{)}_2=1$(Atomic mass of $Ca$)$+2$(Atomic mass of $O$) $+2($Atomic mass of $H)$
$=40+2\left(16\right)+2\left(1\right)$
$=40+32+2$
$=74$