In some chemical reactions, it is found that a large number of colliding molecules have energy more than threshold energy value, yet the reactions are quite slow. Explain.

For a certain reaction, though most of the molecules possess energy greater than the threshold energy. the rate of the reaction is very slow. Explain.

"Lower the activation energy , higher is the rate of a chemical reaction and vice-versa" -explain.

All effective collisions ( having the threshold energy) do not necessarily bring in a chemical change. Explain with an example.

Enzymes are biocatalysts. They catalyse biochemical reaction. In general they reduce activation energy of reactions. Many physico-chemical processes are enzyme mediated. Some examples of enzyme mediated reactions are given below. Tick the wrong entry

Knowing the electron gain enthalpy values for O to O^(-) and OtoO^(2-) as -141 and 702 kJcdotmol^(-1) respectively, how can you account for the formation of a large number of oxides having O^(2-) species and not O^(-) ? (Hint: Consider lattice energy factor in the formation of compounds).

The activation energy for the reaction, 2 HI (g) to +I-2(g), is 209.5 KJ mol _-1 at 581K, Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy.

In any nuclear reaction - (A) The total number of protons and neutrons remains same before and after the reaction. (B) Increase or decrease in the number of protons is equal to the decrease or increase in the number of neutrons. (C) Kinetic energy of the incident particle is approximately 8 MeV or its equivalent. (D) Some energy is released if total mass is reduced.

This question has Statement I and Statement II. Of four choices given after the Statements choose the one that best describes two statements Statement-I : Fraction of total molecules having energy equal to or greater than activation energy = k=Ae^((-E_a)/RT) Statement-II : Activation energy of a chemical reaction is always constant at a given temperature.

Why is the enthalphy change for a chemical reaction more important than internal energy change?