$A$ Van de Graaff generator has a spherical metal shell as an electrode which is at a potential $15 \times 10^6 \ V$. If the dielectric strength of the surrounding medium is $5 \times 10^7 \ V \ m^{-1}$,then the diameter of the shell is: (in $cm$)

Vegetative propagation in mint occurs by

Curie temperature is the temperature above which:

Two cylinders $A$ and $B$ fitted with pistons contain equal amounts of an ideal diatomic gas at $300 \ K$. The piston of $A$ is free to move while that of $B$ is held fixed. The same amount of heat is given to the gas in each cylinder. If the rise in temperature of the gas in $A$ is $30 \ K$,then the rise in temperature of the gas in $B$ is ..... $K$

Which of the following statements is incorrect for $Nostoc$ and $Anabaena$?

The work functions for metals $A, B$ and $C$ are respectively $1.92\, eV, 2.0\, eV$ and $5\, eV$. According to Einstein's photoelectric equation,which of these metals will emit photoelectrons for an incident radiation of wavelength $4100\, \mathring{A}$?