True / False
1. For a first order reaction, the rate of the reaction doubles as the concentration of the reactant (s) doubles. (1986 - 1 Mark)
Solution: True : The rate of reaction of first order is directly proportional to the concentration of reacting substance
2. Catalyst makes a reaction more exothermic. (1987 - 1 Mark)
Solution: False : Catalyst does not make a reaction more exothermic, but decreases the activation energy and hence increase the
rate of reaction.
3. Catalyst does not affect the energy of activation in a chemical reaction. (1989 - 1 Mark)
Solution: False : Catalyst lowers the energy of activation and therefore influences the rate as well as rate constant of the reaction.
4. In β-emission from a nucleus the atomic number of the daughter element decreases by one. (1990 - 1 Mark)
Solution: False : In β-emission the atomic number of the daughter nuclei increases by 1.
5. The rate of an exothermic reaction increases with increasing temperature. (1990 - 1 Mark)
Solution: True : The rate of a reaction increases with increase in temperature because at higher temperature more number of
molecules attain the activation energy.