Exams › JEE Main › Chemistry

For a first-order reaction, find the ratio of the time required for 99.9% completion to the time required for 50% completion (give the answer as the nearest integer).

Correct answer: 10

Solution

The ratio equals log(1000)/log(2) = 3/0.301 ~ 9.97, which rounds to 10.

Related JEE Main Chemistry questions

For the reaction A → products, the half-life is 120 min when the initial concentration of A is 8.0 × 10⁻² M. If the starting concentration is changed to 4.0 × 10⁻² M, the half-life increases to 240 min. What is the reaction order?
For a first-order process A → B, if the rate constant is k and the starting concentration of A is 0.5 M, what is the half-life?
For the elementary gas-phase reaction A(g) + 2B(g) → C(g) + D(g), an experiment starts with initial partial pressures p_A = 0.60 atm and p_B = 0.80 atm. If the partial pressure of C becomes 0.20 atm, then the reaction rate compared with the initial rate is
From the experimental data below for the reaction A + B → products, identify the rate law that fits the observations. Exp. 1: [A] = 0.012, [B] = 0.035, initial rate = 0.1 Exp. 2: [A] = 0.024, [B] = 0.070, initial rate = 0.8 Exp. 3: [A] = 0.024, [B] = 0.035, initial rate = 0.1 Exp. 4: [A] = 0.012, [B] = 0.070, initial rate = 0.8
A radioactive substance is accidentally spread on the floor of a room. If its half-life is 30 days and the initial activity is 10 times the allowed safe level, after how many days will it become safe to enter the room?
For the reversible reaction A2 + B2 ⇌ 2AB, the activation energies are 180 kJ mol⁻¹ for the forward direction and 200 kJ mol⁻¹ for the reverse direction. If a catalyst reduces the activation energy of both directions by 100 kJ mol⁻¹, what will be the enthalpy change of the reaction A2 + B2 ⇌ 2AB in the catalyzed pathway (in kJ mol⁻¹)?

⚔️ Practice JEE Main Chemistry free + battle 1v1 →