Bordeaux mixture was discovered by

The activity of a radioactive sample is measured as $N_0$ counts per minute at $t = 0$ and $N_0/e$ counts per minute at $t = 5$ minutes. The time (in minutes) at which the activity reduces to half its value is

When a capacitor is connected in series to an $LR$ circuit,the alternating current flowing in the circuit

Two particles which are initially at rest,move towards each other under the action of their internal attraction. If their speeds are $v$ and $2v$ at any instant,then the speed of the centre of mass of the system will be

The shaded part of the given figure indicates the feasible region. Then the constraints are:

In $YDSE$ with two identical slits, when the upper slit is covered with a transparent sheet of mica, the second-order minima is observed above the center of the screen and the second-order maxima below it. Which of the following cannot be a possible value of the phase difference caused by the mica sheet?