Effluent from an industry 'A' has a pH of 4.2. The effluent from another industry 'B' has double the hydroxyl (OH^-) ion concentration than the effluent from industry 'A'. pH of effluent from the industry 'B' will be _______.

For a sample of water with the ionic composition shown in the figure below, the carbonate and noncarbonate hardness concentrations (in mg/l as $${\mathrm{CaCO}}_3$$), respectively are:

A water sample has a pH of 9.25. The concentration of hydroxyl ions in the water sample is

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

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