Which of the following is a gas-evolution reaction?
a. 2 c2h6(l) + 7 o2(g) → 4 co2(g) + 6 h2o(g)
b. nh4cl(aq) + koh(aq) → kcl(aq) + nh3(g) + h2o(l) 2
c. h2(g) + o2(g) → 2 h2o(g)
d. licl(aq) + nano3(aq) → lino3(aq) + nacl(aq)
e. none of the above are gas-evolution reactions.

B. NH₄Cl(aq) + KOH(aq) → KCl(aq) + NH₃(g) + H₂O(l)

Explanation:

A gas-evolution reaction is defined as a chemical reaction that produce a gas and where reactants are not in gaseous phase.

Thus, the reactions:

A. 2C₂H₆(l) + 7O₂(g) → 4CO₂(g) + 6H₂O(g)  Is not a gas-evolution reaction because one reactant is a gas.

B. NH₄Cl(aq) + KOH(aq) → KCl(aq) + NH₃(g) + H₂O(l) Is a gas-evolution reaction because one product is the NH₃ that is a gas and reactants are not gases.

C. 2H₂(g) + O₂(g) → 2H₂O(g)  Is not a gas-evolution reaction because the reactants are gases

D. LiCl(aq) + NaNO₃(aq) → LiNO₃(aq) + NaCl(aq) Is not a gas-evolution reaction because there are not gases as products.

I hope it helps!

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