Coagulation

Q. The coagulating power of electrolytes having ions $N{a}^{+},A{l}^{3+}$ and $B{a}^{2+}$ for arsenic aulphide sol increase in the order

1. $A{l}^{3+}<B{a}^{2+}<N{a}^{+}$
2. $B{a}^{2+}<N{a}^{2+}<A{l}^{3+}$
3. $A{l}^{3+}<N{a}^{+}<B{a}^{2+}$
4. $N{a}^{+}<B{a}^{2+}<A{l}^{3+}$

Q. Silver iodide is used in bringing about artificial rain because silver iodide

1. contains iodide ions which are large in size
2. being heavy, its spray brings the water droplets down
3. is easily decomposed in presence of sunlight
4. has crystal structure similar to ice and leads to coagulation

Q.

The coagulation of 100 ml of colloidal solution of gold is completely prevented by addition of 0.25 g of a substance “X” to it before adding 1 ml of 10% NaCl solution. The gold number of “X” is

1. 0.25
2. 2.5
3. 25
4. 250

Q.

The flocculation value of an electrolyte is

1. The reciprocal of coagulating power.
2. The amount of electrolyte in grams required to bring about coagulation of one litre of colloidial sol
3. The amount of electrolyte in milligrams to bring about coagulation of 10 ml of the colloidal sol
4. The amount of the electrolyte in millimoles required to bring about the coagulation of 1 litre of the colloidal sol.

Q. The flocculation value of an electrolyte is

1. The reciprocal of coagulating power
2. The amount of electrolyte in grams required to bring about coagulation of one litre of colloidal sol
3. The amount of electrolyte in milligrams to bring about coagulation of 10ml of collodial sol
4. The amount of the electrolyte in millimoles required to bring about the coagulation of 1 litre of colloidal sol

Q. Ferric chloride is added to stop bleeding because

1. Fe³⁺ ions coagulate positively charged blood solution
2. Fe³⁺ ions coagulate negatively charged blood solution
3. Cl^- ions coagulate positively charged blood solution
4. Cl^- ions coagulate negatively charged blood solution

Q.

A sol has positively charged colloidal particles. Which of the following solutions is required in lowest concentration for coagulation -

1. Na2SO4
2. NaCl
3. K4[Fe(CN)6]
4. ZnCl2

Q. Arrange the following in the decreasing order of their coagulation power: $A{l}^{3+},N{a}^{+},C{a}^{2+}$

1. Al³⁺ = Ca²⁺ = Na⁺
2. Na⁺ > Ca²⁺ > Al³⁺
3. Na⁺ > Al³⁺ > Ca²⁺
4. Al³⁺ > Ca²⁺ > Na⁺

Q.

The capacity to bring about coagulation increases with

1. Valency of an ion

2. Atomic radii

3. Ionic radii

4. Size of an ion

Q. A negatively charged suspension of clay in water is needed for precipitation of minimum amount of -

1. Aluminium chloride
2. Potassium sulphate
3. Sodium hydroxide
4. Hydrochloric acid