Which from following is the most commonly used refrigerant Freon-12?

Which among the following salts turns red litmus blue in its aqueous solution?

Identify ' $B$ ' in the following sequence of reactions.

Acetic acid $\xrightarrow[\Delta]{\text { Thionyl chloride }} \mathrm{A} \xrightarrow{\text { Ammonia }} \mathrm{B}$

A container consists mixture of four gases as $5 \mathrm{~g} \mathrm{H}_2, 8 \mathrm{~g} \mathrm{He}, 50 \mathrm{~g} \mathrm{CO}_2$ and 20 g Ne at a certain temperature. Which of the following gases exerts minimum partial pressure?