(i) Arrange NH_(3)H_(2)O and HF in the order of increasing magnitude of hydrogen bonding and explain the basis for your arrangement. (ii) Can we use concentrated sulphuric acid and pure zinc in the preparation of dihydrogen?

(i) Arrange NH_(3)H_(2)O and HF in the order of increasing magnitude o

1.	(i) Arrange NH_(3)H_(2)O and HF in the order of increasing magnitude of hydrogen bonding and explain the basis for your arrangement. (ii) Can we use concentrated sulphuric acid and pure zinc in the preparation of dihydrogen?
Answer» Solution :(i) 1. Increasing magnitude of HYDROGEN bonding among `NH_(3),H_(2)O` and HF is `HF>H_(2)O>NH_(3)` 2. The EXTENT of hydrogen bonding depends upon electronegativity and the number of hydrogen atoms available for bonding. 3. Among N, F and the increasing order of their electronegativities are N 4. Hence the expected order of the extent of hydrogen bonding is `HF>H_(2)O>NH_(3)` (ii) Conc. `H_(2)SO_(4)` cannot be USED because it acts as an oxidizing agent also and gets reduced to `SO_(2)`. `Zn+2H_(2)SO_(4)(Conc.)toZnSO_(4)+2H_(2)O+SO_(2)` Pure Zn is not used because it is non-porous and reaction will be slow. The impurities in Zn help in constitute of electrochemical couple and speed up reaction.