$A$ body of mass $2 \, kg$ slides down a curved track which is a quadrant of a circle of radius $1 \, m$. All the surfaces are frictionless. If the body starts from rest,its speed at the bottom of the track is ................. $m/s$.

$A$ galvanometer having a coil resistance of $60\,\Omega$ shows full-scale deflection when a current of $1.0\,A$ passes through it. It can be converted into an ammeter to read currents up to $5.0\,A$ by:

$A$ 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:

Which of the following statements is correct for the peroxide ion $(O_2^{2-})$?
$A.$ It has completely filled antibonding molecular orbitals.
$B.$ It is diamagnetic.
$C.$ It has a bond order of $1$.
$D.$ It is isoelectronic with Neon.

$A$ photon collides with a stationary hydrogen atom in the ground state inelastically. The energy of the colliding photon is $10.2 \, eV$. After a time interval of the order of a microsecond,another photon collides with the same hydrogen atom inelastically with an energy of $15 \, eV$. What will be observed by the detector?

In a balanced meter bridge,the resistance of the bridge wire is $0.1 \Omega/cm$. An unknown resistance $X$ is connected in the left gap and $6 \Omega$ in the right gap. The null point divides the wire in the ratio $2:3$. Find the current drawn from a battery of $5 \text{ V}$ having negligible internal resistance. (in $A$)