Which of the following is used as an anesthetic?

The number of integral values of $k$ for which the equation $7 \cos x + 5 \sin x = 2k + 1$ has a solution is:

The number of natural numbers less than $1000$,in which no two digits are repeated,is:

Drops of liquid of density $d$ are floating half immersed in a liquid of density $\rho$. If the surface tension of the liquid is $T$,then the radius of the drop is

The polar equation of the circle with centre $\left(2, \frac{\pi}{2}\right)$ and radius $3$ units is :

The condition that $f(x)=a x^3+b x^2+c x+d$ has no extreme value, is