The order of the differential equation whose solution is $y = a \cos x + b \sin x + c e^{-x}$ is:

Two particles $A$ and $B$ initially at rest move towards each other under a mutual force of attraction. At the instant when the speed of $A$ is $v$ and the speed of $B$ is $2v$,the speed of the centre of mass of the system is

What is the mixture of $MgCl_2$ and $MgO$ called?

In the circuit shown in the figure,the $AC$ source gives a voltage $V = 20 \cos(2000t)$. Neglecting source resistance,the voltmeter and ammeter readings will be

$A$ charge of $1 \mu C$ is divided into two parts such that their charges are in the ratio of $2: 3$. These two charges are kept at a distance $1 \ m$ apart in vacuum. Then,the electric force between them (in $N$) is

The pair of gases responsible for acid rain are