Explanation:

<em>According to <u>le ch</u></em><em><u>-</u></em><em><u>atelier'</u></em><em><u>s</u></em><em><u> </u></em><em><u>principle</u> when a chemical reaction at equilibrium subjected to any stress, then the equilibrium shifts in that direction in which effect of stress is reduced.</em>
When we would add more number of carbon in above reaction then rate of forward reaction will increase to attain the equilibrium again.

Resistance of a material being scratched in known as: Hardness
Answer:
Among Na ,K , Pb , Li , The atom which does not react with water is :
<u>Pb</u>
Explanation:
Li : Reacts slowly with water
Na ,K : Reacts vigorously with water
Pb : It does not reacts with water because :- Pb oxidize in presence of atmospheric oxygen to form lead oxide (PbO) . this PbO form a layer over the surface of Pb and make it inert to water.
They are found in group 3 of the periodic table.