State the third law of thermodynamics.

Identify the correct statement regarding entropy.

At what temperature is the entropy of a perfectly crystalline substance considered to be zero?

Fill in the blanks:
$(i)$ The standard enthalpy of formation of any element in its reference state is considered to be $.........$.
$(ii)$ The scientist $.........$ stated that the entropy of a perfectly crystalline substance decreases with a decrease in temperature.
$(iii)$ At absolute zero temperature,the entropy of a perfectly crystalline substance is zero. This statement represents the $.........$ law of thermodynamics.

The entropy of crystalline substances at absolute zero,according to the third law of thermodynamics,should be taken as:

The law formulated by Dr. Nernst is