Rearrange the following ($I$ to $IV$) in the order of increasing masses:
$I$. $0.5$ mole of $O_3$
$II$. $0.5$ g-atoms of oxygen
$III$. $3.011 \times 10^{23}$ molecules of $O_2$
$IV$. $5.6$ $L$ of $CO_2$ at $STP$

What is the female reproductive organ in mosses called?

If one side of a triangle is double the other and the angles opposite to these sides differ by $60^{\circ}$,then the triangle is

On heating ammonium dichromate and barium azide separately,we get:

Two particles undergo $SHM$ along parallel lines with the same time period $(T)$ and equal amplitudes. At a particular instant,one particle is at its extreme position while the other is at its mean position. They move in the same direction. They will cross each other after a further time:

If $BaCl_2$ ionizes to an extent of $80 \ \%$ in aqueous solution,the value of van't Hoff factor is