Ion concentrations obtained for a groundwater sample (having pH=8.1) are given below.

Ion	$$Ca^{2+}$$	$$Mg^{2+}$$	$$Na^+$$	$$HCO_3^-$$	$$SO_4^{2-}$$	$$Cl^{-}$$
Ionconcentration(mg/L)	100	6	15	250	45	39
Atomic Weight	Ca=40	Mg=24	Na=23	H=1,C=12,O=16	S=32,O=16	Cl=35.5

Total hardness (mg/L as $$CaCO_3$$) present in the above water sample is

A wastewater sample contains $$10^{-5.6}$$ mol/l of OH^- ions at $$25^o$$ C. The pH of this sample is

If tomato juice is having a pH of 4.1, the hydrogen ion concentration will be

Two Samples of Water A and B have pH values of a 4.4 and 6.4 respectively. How many times more acidic sample A is than sample B