Class 11th

This is a short answer type question as classified in NCERT Exemplar

(a) Electron deficient hydrides are those that lack sufficient number of electrons to form typical covalent bonds. Group 13 hydrides, for example (BH₃, AlH₃, etc.).

(b) Electron precise: Electron precise hydrides are those that have the exact number of electrons required to form covalent bonds. Group 14 hydrides, for example (CH₄, SiH₄, GeH₄, SnH₄, PbH₄ etc.). They are tetrahedral in shape.

(c) Electron rich hydrides: Electron rich hydrides are those that have more electrons than are required to create conventional covalent bonds. Hydrides of groups 15 to 17. (NH₃, PH₃, H₂O, H₂S, H₂Se, H₂Te, HF etc.).

This is a short answer type question as classified in NCERT Exemplar

Water demineralization using organic or synthetic ion exchange resins (ion exchange resins):

a. Synthetic resins are insoluble polymeric solids that contain a large hydrocarbon network with reactive acidic or basic groups.   

These are better than Zeolite since they can remove all kinds of cations and anions from water. Demineralised or deionised water is the product of this process.

b. There are two categories of these:

Resins for cation exchange: Acidic groups such as COOH or SO₃H can be found in them. Resin-H+-can be used to represent them.

Mg²⁺            +      2H-resin  →          Mg (resin)₂+       2H⁺

In hard water       Cation exchanger

Ca²⁺  +     2H-resin           →Ca (resin)₂+2H⁺

In hard water  cation exchanger

Anion exchange resins: They have basic groups such as OH- or NH₂.

They may be represented as resin—OH^- or resin. 

SO₄^2-    +   2OH-resin  →   SO₄- (resin)₂+    2OH^-

Hard water  anion exchanger 

Cl^-       +       OH-resin  →   Cl- resin +OH

Hard water  anion exchanger 

This is a short answer type question as classified in NCERT Exemplar

Self ionization of water is known as autoprotolysis of water.

H₂O (l)     +      H₂O (l)             →        H₂O₂ (aq)         +          OH^- (aq)

Acid                Base                          Conjugate acid         Conjugate acid

Significance of autoprotolysis: Due to autoprotolysis, water has the ability to act as an acid as well as a base. Thus, it behaves as an amphoteric substance.

H₂O (l)+NH₃ (aq) ↔ OH^- (aq)+NH₄⁺ (aq)

H₂O (l)+H₂ (aq) ↔ H₃O⁺ (aq)+HS^- (aq)

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans:  option (ii)

The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.
Iron (III) nitrate and potassium thiocyanate react to give deep red coloration.
The reaction is:
Fe³ + aq + SCN⁻↔ [FeSCN]² + aq
yellow deep red
Now, to this solution, if oxalic acid  (H₂C₂O₄) is added, then it reacts with Fe³⁺ ions to form the stable complex ion  [Fe (C₂O₄)3]³⁻, thus decreasing the concentration of Fe³⁺ ions. In accordance with the Le-Chatelier's principle, the decrease in the concentration of Fe³⁺ ions, leads to the decrease in the concentration of  [FeSCN]²⁺ ions which is indicated by the fact that the colour of the solution becomes lighter.