Q$2(25$ marks$)$

a$.20mL$ of a water sample required $6mL$ of $0\mathrm{.}02N{H}_{2}S{O}_4$ to reach the end$-$point with

phenolphthalein as indicator $(pH8\mathrm{.}3),$ and $8mL$ of $0\mathrm{.}02N{H}_{2}S{O}_4$ to reach the end$-$point with

Bromocresol Green $(pH4\mathrm{.}5).$ Name the type of alkalinity indicated by each of these end points

and determine the value of each alkalinity. Also, what other type of alkalinity value can you

calculate from these two observations, and what is its value? $(15$ marks$)$

b$.$ Explain the principal and working of disinfection of water by UV radiation. State its key

advantages and disadvantages over chlorination. $(10$ marks$)$