In the circuit shown below,the ammeter reading is zero. Then the value of the resistance $R$ is (in $\Omega$)

$A$ $2 ~kg$ ball moving at $24 ~ms^{-1}$ undergoes an inelastic head-on collision with a $4 ~kg$ ball moving in the opposite direction at $48 ~ms^{-1}$. If the coefficient of restitution is $2/3$,what are their velocities in $ms^{-1}$ after the impact?

Which of the following statements is incorrect for physical adsorption?

If $a, b, c, d$ are positive real numbers such that $\frac{a}{3} = \frac{a+b}{4} = \frac{a+b+c}{5} = \frac{a+b+c+d}{6}$,then the value of $\frac{a}{b+2c+3d}$ is

An electrically charged particle enters a uniform magnetic field in a direction perpendicular to the field with a velocity $v$. Then,it travels

Liquid $X$ is used in a bubble chamber to detect neutral mesons and gamma photons. Then,$X$ is