One mole of calcium phosphide on reaction with excess of water gives

When $25 \ g$ of a non-volatile solute is dissolved in $100 \ g$ of water,the vapour pressure is lowered by $0.225 \ mm$. If the vapour pressure of water at $20^{\circ}C$ is $17.5 \ mm$,what is the molecular weight of the solute?

$A$ radioactive nucleus $A$ with a half-life $T$ decays into a nucleus $B$. At $t = 0$,there is no nucleus $B$. At some time $t$,the ratio of the number of $B$ to that of $A$ is $0.3$. Then,$t$ is given by:

In the circuit shown in the figure,the potential difference between points $A$ and $B$ is $16 \, V$. The current passing through the $2 \, \Omega$ resistance will be ................. $A$.

On increasing the reverse bias to a large value in a $PN-$junction diode,current

$A$ string is vibrating in its fifth overtone between two rigid supports $2.4 ~m$ apart. The distance between successive node and antinode is (in $~m$)