Companion cells in plants are associated with

Which of the following is an organometallic compound?

$A$ vessel contains $1$ mole of $O_2$ gas (molar mass $32$) at a temperature $T$. The pressure of the gas is $P$. An identical vessel containing $1$ mole of $He$ gas (molar mass $4$) at a temperature $2T$ has a pressure of:

$A$ rubber cube of side $5 ~cm$ has one face fixed,while a tangential force $1800 ~N$ is applied on its opposite face. If the modulus of rigidity of rubber is $2.4 \times 10^6 ~N/m^2$,then the lateral displacement of the strained face is . . . . . . (in $mm$)

In a nuclide,one $a.m.u.$ of mass is dissipated into energy to bind its nucleons. The energy equivalent of this mass is

The effect due to a uniform magnetic field on a freely suspended magnetic needle is as follows: