Chapter 9

Which of the following reactions shows reduction of water? (a) \(2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{Na} \rightarrow 2 \mathrm{NaOH}+\mathrm{H}_{2}\) (b) \(6 \mathrm{CO}_{2}+12 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}+6 \mathrm{H}_{2} \mathrm{O}+6 \mathrm{O}_{2}\) (c) \(2 \mathrm{~F}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 4 \mathrm{H}^{+}+4 \mathrm{~F}^{-}+\mathrm{O}_{2}\) (d) \(\mathrm{P}_{4} \mathrm{O}_{10}+6 \mathrm{H}_{2} \mathrm{O} \rightarrow 4 \mathrm{H}_{3} \mathrm{PO}_{4}\)

Hydrolysis of \(\mathrm{SiCl}_{4}\) gives (a) \(\mathrm{Si}(\mathrm{OH})_{4}\) (b) \(\mathrm{SiOCl}_{2}\) (c) \(\mathrm{SiO}_{2}\) (d) \(\mathrm{H}_{2} \mathrm{SiO}_{4}\)

How many hydrogen bonded water molecules are associated with \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) ? (a) Five (b) One (c) Four (d) Three

During hydrate formation from aqueous solution, water can be associated in different forms. Indicate the wrong combination. (i) Coordinated water - \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+} 3 \mathrm{Cl}^{-}\) (ii) Interstitial water - \(\mathrm{BaCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) (iii) Hydrogen bonded water \(\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\right]^{2+} \mathrm{SO}_{4}^{2-} \cdot \mathrm{H}_{2} \mathrm{O}\) (a) (i) (b) (ii) (c) (iii) (d) None of these.

The temporary hardness of water due to calcium bicarbonate can be removed by adding (a) \(\mathrm{CaCO}_{3}\) (b) \(\mathrm{CaCl}_{2}\) (c) \(\mathrm{HCl}\) (d) \(\mathrm{Ca}(\mathrm{OH})_{2}\)

A water sample is said to contain permanent hardness if water contains (a) sulphates and chlorides of calcium and magnesium (b) carbonates of calcium and magnesium (c) bicarbonates of calcium and magnesium (d) sulphates and chlorides of sodium and potassium.

Presence of water can be detected by (a) adding a drop to anhydrous copper sulphate which changes its colour from white to blue (b) by boiling and testing for the presence of \(\mathrm{H}_{2}\) and \(\mathrm{O}_{2}\) (c) by seeing its colour and transparency (d) by checking the production of lather when mixed with soap.

Which of the following is not a disadvantage of using hard water? (a) In production of steam in boilers (b) Formation of scales in cooking utensils (c) In cooking, bathing and washing (d) In ion exchangers

Polyphosphates like sodium hexametaphosphate (calgon) are used as water softening agents because they (a) form soluble complexes with anionic species (b) precipitate anionic species (c) form soluble complexes with cationic species (d) precipitate cationic species.

What is meant by demineralised water? (a) Water free from cations and anions. (b) Water free from minerals dissolved in it. (c) Water free from impurities. (d) Water free from \(\mathrm{Na}^{+}\)and \(\mathrm{K}^{+}\)ions.