Question

Question 6.3 The enthalpies of all elements in their standard states are:

(i) unity

(ii) zero

(iii) < 0

(iv) different for each element

Class XI Thermodynamics Page 182

Answer 1

zero. as there is no change in their formation.

Answer 2

the enthalpies of all elements in their standard states are taken as zero.

Because the standard state of an elementary substance means the most stable form of that substance at room temperature { 298K} and 1 bar pressure.

Hence, option (ii) is correct.