Which property of hydrogen distinguishes it from alkali metals?

What are the products formed when ammonia reacts with excess chlorine?

Assertion : For a reaction $2NH_{3(g)} \to N_{2(g)} + 3H_{2(g)}$ ; $\Delta H > \Delta E$
Reason : Enthalpy change is always greater than internal energy change.

The mechanism of the reaction $2NO_2 + F_2 \to 2NO_2F$ is given by:
$(i)$ $NO_2 \xrightarrow{slow} NO_2^*$
$(ii)$ $NO_2^* + F_2 \xrightarrow{fast} NO_2F + F$
$(iii)$ $F + NO_2 \xrightarrow{fast} NO_2F$
Select the correct statement regarding this reaction.

Guard cells are helpful in:

$A$ coil is suspended in a uniform magnetic field with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil,it starts oscillating and is very difficult to stop. However,if an aluminium plate is placed near the coil,it stops. This is due to: