Which of the following statements are true?

(A) Decomposition of gaseous ammonia on a hot platinum surface is a zero order reaction.
(B) The rate of a reaction increases with the passage of time.
(C) A catalyst does not change the equilibrium of a reaction.
(D) The molecularity of a reaction can be zero, fraction and negative.

Choose the correct answer from the options given below:

(A) and (C) only

The correct answer is Option (2) → (A) and (C) only

(A) True: The decomposition of gaseous ammonia (2NH₃ → N₂ + 3H₂) on a hot platinum surface is a classic example of a zero-order reaction. This occurs because the platinum surface becomes fully saturated with ammonia molecules at typical pressures, making the rate independent of ammonia concentration (rate = k).

(B) False: The rate of a reaction generally decreases with time because reactant concentrations decrease as the reaction progresses (except in rare cases like autocatalytic reactions). For most reactions, the rate does not increase with time.

(C) True: A catalyst speeds up both the forward and reverse reactions equally by lowering the activation energy for both paths. It helps attain equilibrium faster but does not shift the equilibrium position or change the equilibrium constant.

(D) False: Molecularity is the number of reactant molecules involved in an elementary step and is always a positive whole number (1, 2, 3, etc.). It cannot be zero, fractional, or negative, as that would have no physical meaning in terms of simultaneous collisions. (Order of reaction, however, can be zero, fractional, or negative.)