What do you mean by activity and selectivity of catalysts?

Explanation

i) Activity: It is the capacity of a catalyst to increase the speed of the chemical reaction. Ega in some cases, the extent to whicl speed af the reactiön is increased is as highas .10^ to . times. Eg. Combination of .H., and .O_1. in the presence of platinum, catalyst to form .H_2 O. with explosive violence js an example of catalyst activity: In the absenee of the catalyst. .H_2.,and .O_2. do not combine and can be stored as such fơr an indefinite period.
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2 H_2+O_2 stackrelPtlongrarrarrow 2 H, O^t
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ii) Selectivity - It is the ability of a catalyst to direct the reaction to form particular products excluding others.
, 1) .C O. and .H_2. react to form different products.
.=Eg.
in presence of different catalyst.
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