If the maximum velocity with which an electron can be emitted from a photocell is $4 \times 10^8 \,cm/sec$,the stopping potential is ............ $V$ (mass of electron $= 9 \times 10^{-31} \,kg$).

$A$ tangent is drawn to the ellipse $\frac{x^2}{27} + y^2 = 1$ at the point $(3\sqrt{3} \cos \theta, \sin \theta)$,where $\theta \in (0, \pi/2)$. The value of $\theta$ for which the sum of the intercepts on the axes made by this tangent is minimum,is:

$A$ wheel is rotating at $900 \ r.p.m.$ about its axis. When the power is cut-off,it comes to rest in $1 \ minute$. The angular retardation in $rad/s^2$ is

The figure below shows two paths that may be taken by a gas to go from a state $A$ to a state $C$. In process $AB$,$400 \, J$ of heat is added to the system and in process $BC$,$100 \, J$ of heat is added to the system. The heat absorbed by the system in the process $AC$ will be ............. $J$.

Which of the following is the strongest Lewis base?

$A$ proton (mass $m$ and charge $+e$) and an $\alpha$-particle (mass $4m$ and charge $+2e$) are projected with the same kinetic energy at right angles to a uniform magnetic field. Which one of the following statements is true?