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

In the isoelectronic series of metal carbonyls,the $CO$ bond strength is expected to increase in the order:

The molecular formula of diphenylmethane is $C_{13}H_{12}$. How many structural isomers are possible when one of the hydrogen atoms is replaced by a chlorine atom?

An aircraft executes a horizontal loop of radius $9 \ km$ at a constant speed of $540 \ km/h$. The wings of the aircraft are banked at an angle of (Acceleration due to gravity $g = 10 \ m/s^2$):

Four charges are placed at the circumference of the dial of a clock as shown in the figure. If the clock has only an hour hand,then the resultant force on a positive charge $q_0$ placed at the center points in the direction which shows the time as: (in $:30$)

Assertion $(A)$: $A$ catalyst increases the rate of a reaction.
Reason $(R)$: In the presence of a catalyst,the activation energy of the reaction increases.
The correct answer is