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 $= 9 \times 10^{-31} \,kg$).

If $f: R \rightarrow R$ is defined by $f(x) = 7 + \cos(5x + 3)$ for $x \in R$,then the period of $f$ is

The locus of a point such that the sum of its distances from the points $(0, 2)$ and $(0, -2)$ is $6$,is

Which of the following $0.05 \, M$ aqueous solution will have the lowest freezing point?

The rate of steady volume flow of water through a capillary tube of length $l$ and radius $r$ under a pressure difference of $P$ is $V$. This tube is connected with another tube of the same length but half the radius in series. Then the rate of steady volume flow through them is (The pressure difference across the combination is $P$).

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$ :
Assertion $A$: Size of $Bk^{3+}$ ion is less than $Np^{3+}$ ion.
Reason $R$: The above is a consequence of the actinoid contraction.
In the light of the above statements,choose the correct answer from the options given below: