Question

JEE MAINS PHYSICS QUESTION SEPTEMBER 2020

Answer 1

Answer:

For Adiabatic process,

$</strong><strong>∆</strong><strong>q = 0$

Isothermal process,

$</strong><strong>∆</strong><strong>U</strong><strong> = 0$

For isobaric process,

Pressure is constant, $</strong><strong>∆</strong><strong>p = 0$

And,

$</strong><strong>∆</strong><strong>U</strong><strong> </strong><strong>≠</strong><strong> 0 </strong><strong>,</strong><strong>∆</strong><strong>q</strong><strong> </strong><strong>≠</strong><strong> 0 </strong><strong>,</strong><strong>∆</strong><strong>w</strong><strong> </strong><strong>≠</strong><strong> 0$

In isochoric process,

Work done,

$</strong><strong>∆</strong><strong>w</strong><strong> </strong><strong>=</strong><strong> 0$

Answer 2

we have to match the following columns .

I Adiabatic (A) ∆U = 0

II isothermal (B) ∆W = 0

III isobaric (C) ∆Q = 0

IV isochoric. (D) ∆U ≠ 0

∆Q ≠ 0

∆W ≠ 0

solution : in Adiabatic process ⇒heat remains constant. i.e., ∆Q = 0

so, I ⇒(C)

in isothermal process ⇒temperature remains constant, this implies internal energy change must be zero. i.e., ∆U = 0

so, II ⇒(A)

in isobaric process ⇒pressure remains constant.

but ∆W = P∆V ≠ 0

∆U = nCv∆T ≠ 0

∆Q = ∆U + ∆W ≠ 0

so, III ⇒(D)

in isochoric process ⇒volume remains constant, this implies work done must be zero.

i.e., ∆W = 0

IV ⇒(B)

Therefore the correct option is (3)