Why does the rate of a reaction increase with rise in temperature?
At higher temperatures, larger fraction of colliding particles can cross the energy barrier (i.e., the activation energy) which leads to faster rate.
Oxygen is available in plenty in air yet fuels do not burn by themselves at room temperature. Explain.
For combustion reactions, activation energy of fuels is very high at room temperature. So, fuels do not burn by themselves at room temperature.
What is the probability of reaction with molecularity higher than three very rare?
According to collision theory, we know that to complete any chemical reaction there must be effective collision between reactant particles and they must have minimum sufficient energy. The probability of more than three molecules colliding simultaneously is very small. Hence, possibility of molecularity being three is very low.
Why does the rate of any reaction generally decreases during the course of the reaction?
The rate of a reaction depends on the concentration of the reactants. As the reaction proceeds in forward direction, concentration of reactant decreases and that of products increases. So, the rate of reaction generally decreases during the course of reaction.
Thermodynamic feasibility of the reaction alone cannot decide the rate of the reaction. Explain with the help of one example.
Thermodynamically the conversion or diamond to graphite is highly feasible but this reaction is very slow because its activation energy is high.
Hence, thermodynamic feasibility of the reaction alone cannot decide the rate of reaction.