Permanent hardness of water is due to the presence of
(1) bicarbonates of sodium and potassium
(2) bicarbonates of sodium and potassium
(3) chlorides and sulphates of calcium and matgnesium.
(4) bicarbonates of calcium and magnesium.
(5) phosphates of sodium and potassium

The hydroxides and carbonates of sodium and potassium are easily soluble in water while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain.

Explain the significance of sodium, potassium, magnesium and calcium in biological fluids.

According to the recommendations given by WHO/UNICEF. In ORS, what are the quantities of Sodium bicarbonate and Potassium chloride in I litre of water?

This question has Statement I and Statement II. Of the four choices given after the Statements, choose the one that best describes the two Statements. 15. Statement -1: Potassium carbonate can be prepared by Solvay process like sodium carbonate using potassium chloride as starting material. Statement - II : Potassium carbonate is obtained as one of the products when potassium superoxide reacts with carbon dioxide.

The ionic bond between sodium and chloride ion is stronger than that between potassium and chloride ion. Explain.

This question has Statement I and Statement II. Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement - I : Sodium bicarbonate generally precipitates normal carbonate from magnesium chloride solution. Statement - II: Sodium carbonate generally precipitates basic carbonate from magnesium chloride solution.

Among the sulphate salts of lithium, sodium, potassium and rubidium, which salt does not form double salt?

Correct relationship between pH of isomolar solutions of sodium oxide (pH_1) , sodium sulphide (pH_2) , sodium selenide (pH_3) and sodium telluride (pH_4) is-

Alkali metals on combustion in excess of air form different type of oxides depending on the size of metal cations e.g . lithium forms mainly the oxide Li_2O , sodium forms peroxide and some super oxides NaO_2 and potassium, Rubidium and caesium form the superoxides, MO_2 . The stability of peroxide and superoxide increases, as the size of the metal cation increases because of the stabilisation of larger anion by larger cations through lattice energy effect. These oxides are easily hydrolysed by water. The oxides and the peroxides are colourless when pure, but the superoxides are yellow or orange in colour. Peroxide and superoxide of sodium and potassium are widely used as oxidising agent and as air purifier in space capsules, submarines and breathing mask. When sodium reacts with excess of oxygen at 350^@ C , the oxidation number of oxygen per atom changes from: