Ncert Solutions Chemistry Class 11th

This is a multiple choice answer as classified in NCERT Exemplar

Option (i) and (ii)

Presence of calcium and magnesium salts in the form of hydrogen carbonate, chloride and sulphate in water makes water 'hard'.

This is a multiple choice answer as classified in NCERT Exemplar

Option (iii) and (iv)

The presence of extensive hydrogen bonding between water molecules gives it remarkable features in the condensed phase (liquid and solid phases). In comparison to H₂S and H₂Se, this results in a high freezing point, high boiling point, high heat of vaporisation, and high heat of fusion.

This is a multiple choice answer as classified in NCERT Exemplar

Option (i) and (ii)

When an electron is removed from a hydrogen atom, the nucleus decreases to 1.5 * 10^-3 pm in size. When compared to usual atomic and ionic sizes of 50 to 200 pm, this is exceedingly small. As a result, H+ does not exist independently and is always bound to other atoms or molecules.

This is a multiple choice answer as classified in NCERT Exemplar

Option (i) and (iii)

Heavy water is utilised as a moderator in nuclear reactors and exchange reactions, and it is more associated with water due to its higher mass.

This is a multiple choice answer as classified in NCERT Exemplar

Option (i) and (ii)

The combination of CO and H₂ is known as water gas. This mixture of CO and H₂ is also known as synthesis gas or 'syngas' since it is used to make methanol and other hydrocarbons.

This is a multiple choice answer as classified in NCERT Exemplar

Option (iii) and (iv)

H⁺ does not exist freely and is always associated with other atoms or molecules. It has an extremely high ionisation enthalpy and does not have metallic properties under normal conditions, unlike alkali metals.

This is a multiple choice answer as classified in NCERT Exemplar

Option (i)

Group 6

From group 6, only chromium forms CrH.

This is a multiple choice answer as classified in NCERT Exemplar

Option (i)

Groups 7,8, 9

Explanation: The metals belonging to group 7, 8 and 9 do not have tendency to form hydrides.

This is a multiple choice answer as classified in NCERT Exemplar

Option (iii)

Na₆P₆O₁₈

Sodium hexametaphosphate (Na₆P₆O₁₈), commercially called 'calgon', is used to remove hardness from water.

This is a multiple choice answer as classified in NCERT Exemplar

Option (i)

Ca²⁺

Water becomes 'hard' when it contains calcium and magnesium salts in the form of hydrogen carbonate, chloride, and sulphate.