#[A]

For A(g) + 2B(g) 2C(g) , if Kc = 4 and [C] = 0.8 M , [B] = 0.4 M at equilibrium, what is [A] ?

Kc = ([C]²/[A][B]²) = 4 , 4 = ((0.8)²/[A](0.4)²) = (0.64/[A] × 0.16) , 4 × 0.16 [A] = 0.64 , 0.64 [A] = 0.64 , [A] = 1.0 M .

Ref: NCERT Class 11 Chemistry > Chapter 6: Equilibrium > Topic: Physical Equilibrium - Solid-Liquid Gas-Liquid and Henry's Law