KVPY 2020-21 SA Exam Previous Papers

AB → • Isothermal expansion (i.e. ${\mathit{T}}_{\mathit{A}}={\mathit{T}}_{\mathit{B}}$ )
• On moving A to B, volume increases and P decreases so, entropy will increase.
BC → • Adiabatic expansion, so cooling occur.
So ${\mathit{T}}_{\mathit{B}}>{\mathit{T}}_{\mathit{C}}$
• For adiabatic process, ∆S = 0, means entropy remains same.
CD → • Isothermal compression (i.e. ${\mathit{T}}_{\mathit{C}}={\mathit{T}}_{\mathit{D}}$ )
• On moving C to D, volume decreases and P increases so, entropy will decrease.
DA → • Adiabatic compression, so heating occur.
So ${\mathit{T}}_{\mathit{A}}>{\mathit{T}}_{\mathit{D}}$
• For adiabatic process, ∆S = 0 means entropy remains same