A system irradiated for 10 min. is found to absorb $$3 \times {10^{18}}$$  quanta per sec. If the amount of substance decomposed is $$3 \times {10^{ - 3}}\,mol$$
$$\left( {{N_A} = 6 \times {{10}^{23}}} \right).$$    The quantum efficiency of the reaction is

Solution :
$$\eqalign{ & {\text{Quantum efficiency}} \cr & = \frac{{{\text{Number of moles of substance reacted}}}}{{{\text{Number of Quanta absorbed}}}} \cr & = \frac{{3 \times {{10}^{ - 3}} \times 6 \times {{10}^{23}}}}{{3 \times {{10}^{18}} \times 60 \times 10}} \cr & = 1 \cr} $$