$A$ ball is allowed to fall from a height of $10\, m$. If there is $40\%$ loss of energy due to impact,then after one impact,the ball will rise to a height of ......... $m$.

The number of turns in the primary and secondary coils of a transformer are $50$ and $200$ respectively. If the current in the primary coil is $4 ~A$,then the current in the secondary coil is: (in $~A$)

The half-life of a radioactive substance is $20 \text{ minutes}$. The time interval between $20\%$ and $80\%$ decay is ........ $\text{minutes}$.

If $f(x) = (x^2 - 1)^7$,then $f^{(14)}(x)$ is equal to

Which is the major product of the following reaction?

Which of the following pairs of orbitals possess two nodal planes?