$\lim _{x \rightarrow 0} \frac{\tan x - \sin x}{x^3}$ is equal to

Current $I$ is flowing in a conductor shaped as shown in the figure. The radius of the curved part is $r$ and the length of the straight portions is very large. The value of the magnetic field at the centre $O$ will be

If the pair of straight lines given by $Ax^2+2Hxy+By^2=0$ $(H^2 > AB)$ forms an equilateral triangle with the line $ax+by+c=0$,then $(A+3B)(3A+B)$ is equal to:

The binding energy per nucleon versus mass number curve for nuclei is shown in the figure. $W, X, Y$ and $Z$ are four nuclei indicated on the curve. The process that would release energy is:

In the circuit shown below,the $AC$ source has voltage $V = 20 \cos(\omega t)$ with $\omega = 2000 \, rad/sec$. The amplitude of the current will be nearest to.....$A$

Which of the following is the correct electronic configuration of $Cu$ (atomic number $29$)?