The ratio of the centripetal accelerations of the electron in two successive orbits of hydrogen is $81: 16$. Due to a transition between these two states,the angular momentum of the electron changes by ($h$ - Planck's constant).

If $PM$ is the perpendicular from $P(2, 3)$ onto the line $x+y=3$,then the coordinates of $M$ are

Consider the following statements $A$ and $B$ and identify the correct answer given below:
$(A)$ $A$ body initially at rest is acted upon by a constant force. The rate of change of its kinetic energy varies linearly with time.
$(B)$ When a body is at rest,it must be in equilibrium.

There are two holes,one each along the opposite sides of a wide rectangular tank. The cross-section of each hole is $0.01 ~m^2$ and the vertical distance between the holes is $1 ~m$. The tank is filled with water. The net force on the tank in newtons when the water flows out of the holes is (Density of water $= 1000 ~kg/m^3$,$g = 10 ~m/s^2$):

$A$ cell is connected between the points $A$ and $C$ of a circular conductor $\text{ABCD}$ of center $O$ with angle $\angle AOC = 60^{\circ}$. If $B_1$ and $B_2$ are the magnitudes of the magnetic fields at $O$ due to the currents in arc $\text{ABC}$ and arc $\text{ADC}$ respectively,the ratio $\frac{B_1}{B_2}$ is

$A$ solid element $Y$ conducts electricity and forms two types of chlorides: $YCl_n$ (a colorless volatile liquid) and $YCl_{n-2}$ (a colorless solid). To which group does element $Y$ belong?