Chemistry NCERT Exemplar Solutions Class 12th Chapter Five

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: (i) and  (iv)

Negatively charged emulsion can  be  precipitated by oppositely  charged electrolyte. Na+ and K+ from the  electrolyte can  neutralize  the  negatively  charge  emulsion and  precipitate  the  colloid so the answers are (i) and  (iv).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: (ii) and (iv)

Emulsions can be broken into constituent liquids by heating, freezing and centrifuging hence the answer is (ii) and (iv).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans:  (ii) and (iv)

The presence of equal and similar charges on colloidal particles is largely responsible in providing stability to the colloidal

solution, because the repulsive forces between charged particles having same charge prevent them from coalescing or

aggregating when they come closer to one another. The Brownian movement has stirring effect which does not permit the particles to settle and thus, is responsible for the stability of sols hence the answer is (ii) and (iv).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans:   (ii) and (iii)

H₂ molecule on an activated charcoal is adsorbed to a very little extent in comparison to easily liquefiable gases because it has (a) Very weak van there Waals force of attraction (b) Very low critical temperature hence the answer is (ii) and (iii).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: (i) and (iii)

Freundlich gave an empirical relationship between the quantity of gas adsorbed by unit mass of solid adsorbed and pressure at a particular temperature.

$\frac{\mathrm{x}}{\mathrm{p}}$ =kp $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\mathrm{n}$}\right.$

If $\frac{1}{\mathrm{n}}$  = 0 ; $\frac{\mathrm{x}}{\mathrm{m}}$  = k xtent of adsorption is independent of pressure

When n=0 ; $\frac{\mathrm{x}}{\mathrm{m}}$  = kp

$\frac{\mathrm{x}}{\mathrm{m}}$  vs p is a line

parallel to x-axis

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: (i) and (ii)

The action of a catalyst is selective in nature and so a substance which acts as a catalyst in one reaction may fail to catalyse another reaction. They also do not change the enthalpy of reaction hence the answer is (i) and (ii).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: (ii) and (iii)

The formation of micelles takes place only above a particular temperature which is the Kraft temperature (Tk ) and above a particular concentration i.e., the critical micelle concentration (CMC). Upon dilution, these colloids revert back to the individual ions hence the answer is (ii) and (iii).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: Correct option is (ii)

In the figure adsorption of coloured particle from charcoal is shown. Solution of raw sugar is filtered by animal charcoal

and yellowish brown colour of raw sugar is adsorbed and filterate is colourless which gives white colour on crystallization

hence the answer is (ii).

This is a Multiple Choice Type Questions as classified in NCERT Exemplar

Ans: Correct answer is (iv)

Charge on the sol particles can be a result of the following:

Due to electron capture by sol particles during electrodispersion of metals,

Due to preferential adsorption of ions from solution and/or

Due to formulation of electrical double layer.

Hence the correct answer is (iv)