If $\log _{27}(\log _3 x) = \frac{1}{3}$, then the value of $x$ is

Two cylinders $A$ and $B$ fitted with pistons,contain equal number of moles of an ideal monoatomic gas at $400 ~K$. The piston of $A$ is free to move while that of $B$ is held fixed. Same amount of heat energy is given to the gas in each cylinder. If the rise in temperature of the gas in $A$ is $42 ~K$,the rise in temperature of the gas in $B$ is $(\gamma = 5/3)$. (in $~K$)

Which of the following plants are used as green manure in crop fields and in sandy soils?

Which of the following substances would quickly absorb oxygen?

The electric field associated with an $e.m.$ wave in vacuum is given by $\vec E = \hat i\,40\,\cos \left( {kz - 6 \times {{10}^8}\,t} \right)$,where $E$,$z$,and $t$ are in $V/m$,$m$,and $s$ respectively. The value of the wave vector $k$ is ....... $m^{-1}$.

$A$ bullet of mass $0.02\, kg$ travelling horizontally with velocity $250\, ms^{-1}$ strikes a block of wood of mass $0.23\, kg$ which rests on a rough horizontal surface. After the impact,the block and bullet move together and come to rest after travelling a distance of $40\, m$. The coefficient of sliding friction of the rough surface is $(g = 9.8\, ms^{-2})$