The number of unpaired electrons in an $O_2$ molecule is

The full form of $NAD$ is

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

The number of non-trivial solutions of the system $x-y+z=0, x+2y-z=0, 2x+y+3z=0$ is

Which of the following statements is incorrect regarding viruses?

At $T(K)$,$100 \ L$ of dry oxygen is present in a sealed container. It is subjected to silent electric discharge,till the volumes of oxygen and ozone become equal. What is the volume (in litres) of ozone formed at $T(K)$?