$64$ small drops of mercury,each of radius $r$ and charge $q$,coalesce to form a big drop. The ratio of the surface charge density of each small drop to that of the big drop is:

If vapour pressures of pure liquids $A$ and $B$ are $300 \ torr$ and $800 \ torr$ respectively at $25 \ ^oC$. When these two liquids are mixed at this temperature to form a solution in which mole percentage of $B$ is $92$,then the total vapour pressure is observed to be $0.95 \ atm$. Which of the following is true for this solution?

Select the correct statement from the following.

If $f(x) = \frac{x^2-10x+25}{x^2-7x+10}$ and $f$ is continuous at $x = 5$, then $f(5)$ is equal to

In the concentration of $PbS$ containing $ZnS$ as impurity,the depressant used is:

$A$ stretched wire of length $110 \ cm$ is divided into three segments whose frequencies are in the ratio $1 : 2 : 3$. Their lengths must be