MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The given chemical equation is: C _2 H _5 OH (l) + 3 O _2(g) 2 CO _2(g) + 3 H _2 O (l) The change in the number of moles of gaseous species, n_g, is calculated as: n_g = n_ p(g) - n_ r(g) = 2 - 3 = -1 The relationship between enthalpy change ( H) and internal energy change ( U) is given by: H = U + n_g RT Given: H = -1366.5 kJ mol ^ -1 R = 8.314 10^ -3 kJ K ^ -1 mol ^ -1 T = 27^ C = 300 K Substituting the values into the equation: -1366.5 = U + (-1) (8.314 10^ -3 ) 300 -1366.5 = U - 2.4942 U = -1366.5 + 2.4942 = -1364.0058 kJ mol ^ -1 Rounding to one decimal place, we get -1364.0 kJ mol ^ -1 . Answer: -1364.0 kJ mol ^ -1