JEE Advanced2011ChemistryThermodynamics (C)Actual
Match the transformation in Column I with appropriate options in Column II.
Options
- A(A) p,q,r,s, (B) r,s, (C) t, (D) p,q
- B(A) p,s, (B) p,s, (C) s, (D) p,q,s
- C(A) p,s, (B) q,r, (C) s, (D) p,q
- D(A) p,r,s, (B) r,s, (C) t, (D) p,q,t
Correct answer
D. (A) p,r,s, (B) r,s, (C) t, (D) p,q,t
Step-by-step solution
(A) CO ₂( ~s ) CO ₂( ~g ) It is just a phase transition (sublimation) as no chemical change has occurred. Sublimation is always endothermic. Product is gas, more disordered, hence s is positive. (B) CaCO ₃( ~s ) CaO ( s )+ CO ₂( ~g ) It is a chemical decomposition, not a phase change. Thermal decomposition occur at the expense of energy, hence endothermic. Product contain a gaseous species, hence, S>0 . (C) 2 H H ₂( ~g ) A new H - H covalent bond is being formed, hence, H < 0 . Also, product is less disordered than