What is the full form of $ARC$?

$\operatorname{cosec} 15^{\circ} + \sec 15^{\circ}$ is equal to :

Select the incorrect pair:

Given three points $P, Q, R$ with $P(5, 3)$ and $R$ lies on the $x-$ axis. If the equation of $RQ$ is $x - 2y = 2$ and $PQ$ is parallel to the $x-$ axis,then the centroid of $\Delta PQR$ lies on the line

In which of the following circuits is the current maximum just after the switch $S$ is closed?

Which of the following is true for the gaseous state?