Catalyst doesnot change the equilibrium constant it only helps in reaching the equilibrium at a faster rate.

The time taken for half the reaction to complete, i.e., the time in which the concentration of a reactant is reduced to half of its original value is called half-life period of the reaction. But it is impossible to perform 100% of the reaction. Whole of the substance never reacts because in every half-life, 50% of the substance reacts. Hence, time taken for 100% completion of a reaction is infinite. 

Collision theory is only applicable to bimolecular reaction.

Rate of reaction is dependent on concentration of reactant

The correct answer is Option C.

Let R be the rate of reaction.
For first order reaction,
R=K[A]¹
⇒K=R[A]^-1
Whereas, K and [A] are rate constant and initial concentration of reactant respectively.
Therefore,
Unit of rate constant =(mol L^-1 )^1-n sec^-1
For first order reaction, n=1
Unit of rate constant = sec^-1
Hence the unit of rate constant for first order reaction is sec^-1 .

Elementary reaction are one step reactions.

Rate constant is independent of concentration of reactant.

In acid catalysed hydrolysis of ethylacetate the water is in excess so it is pseudo 1st order reaction.

Decomposition of N₂ O₅ is 1st order reaction.

Since order of reaction with respect to RCl is one so if conc of RCl is halfed the rate of reaction will also become half.

Photochemical reaction between H₂  and Cl₂  is 0 zero wrt to reactants.

For every 100 rise in temperature rate of reaction increases by factor of 2 or 3.

Rate of reaction is determined by slowest step.