Identify correct statement for the reaction.

$$ \mathrm{I}_2+\mathrm{KClO}_3 \xrightarrow{\Delta} \mathrm{ICl}+\mathrm{KIO}_3 $$

Calculate the number of atoms present per unit cell if product of density and volume of unit cell is $1.8 \times 10^{-22} \mathrm{~g}$.

[Mass of an atom $=4.5 \times 10^{-23} \mathrm{~g}$ ]

Calculate the change in internal energy of the system if 25 kJ of work done by the system and it absorbs 10 kJ of heat.

$$ \text { Identify ' } Z \text { ' in the following reaction. } $$