The limiting friction between two bodies in contact is independent of

In a resonance tube experiment,a tuning fork resonates with an air column of length $12 ~cm$ and again resonates when the air column is $38 ~cm$ long. The end correction will be: (in $~cm$)

$1\, g$ of hydrogen is converted into $0.993\, g$ of helium in a thermonuclear reaction. The energy released is

If $ab \neq 0$ and the sum of the coefficients of $x^7$ and $x^4$ in the expansion of $\left(\frac{x^2}{a}-\frac{b}{x}\right)^{11}$ is $0$,then

Two dice are rolled simultaneously. The probability that the sum of the two numbers on the dice is a prime number is:

$A$ body of mass $m$ hangs at one end of a string of length $l$,the other end of which is fixed. It is given a horizontal velocity so that the string just reaches a position where it makes an angle of $60^o$ with the vertical. The tension in the string at the mean position is: