The RATE CONSTANT ($k$) of a reaction is

1. NCERT §3.2 introduces the rate law: $\text{rate} = k[A]^a[B]^b$, where $k$ is the rate constant and $a, b$ are reaction orders. 2. The rate constant $k$ captures temperature-dependent intrinsic kinetics: it depends on $T$ via the Arrhenius relation $k = A e^{-E_a/RT}$, and a catalyst can lower $E_a$ (and thus raise $k$). 3. Crucially, $k$ does NOT depend on the concentrations of reactants — those appear separately in the rate law. 4. The rate ITSELF depends on both $k$ and current concentrations, so option A is wrong (rate ≠ $k$). Option C confuses rate constant with thermodynamic quantities. Option D is wrong — $k$ and half-life are related but not equal. _Source: NCERT Class 12 Chemistry Part 1, Ch 3, §3.2 (Rate Constant and Order of Reaction), p. 6–7._