Find the oxidation state of sodium in $Na_{2}O_{2}$.

The perimeter of a sector is a constant. If its area is to be maximum,the sectorial angle is:

The pair of compounds,which cannot exist together in a solution is

$A$ neutrino is a particle,which is

Three liquids of densities $\rho_1, \rho_2$ and $\rho_3$ (with $\rho_1 > \rho_2 > \rho_3$) having same value of surface tension $T$,rise to the same height in three identical capillaries. Angle of contact $\theta_1, \theta_2$ and $\theta_3$ respectively obey

$A$ mass of $0.5\, kg$ moving with a speed of $1.5\, m/s$ on a horizontal smooth surface,collides with a nearly weightless spring of force constant $k=50\, N/m$. The maximum compression of the spring would be ................. $m$.