Methods to Form Lyophobic Colloids

Q.

The stabilization of a dispered phase in a lyophobic colloid is due to:

1. the viscosity of the medium
2. theadsorption of charged substances on dispersed phase
3. thelarge electro-kinetic potential developed in the colloid
4. the formation of an electrical layer between two phases

Q.

The stabilization of a dispered phase in a lyophobic colloid is due to:

1. the viscosity of the medium

2. theadsorption of charged substances on dispersed phase

3. the formation of an electrical layer between two phases

4. thelarge electro-kinetic potential developed in the colloid

Q. Which of the following statements are true about peptization? A. A colloidal sol is converted into precipitate B. It is done in the presence of a small electrolyte C. Charges develop on the precipitate during this process D. The charges developed during this process further breaks up into smaller particles of the size of colloids.

1. A, B, D
2. A, B, C, D
3. A, B, C
4. B, C, D

Q.

Colloidal solution of arsenious sulphide can be prepared by

[AMU 1985]

1. Peptization

2. Double decomposition

3. Electrodispersion method

4. Hydrolysis]

Q. Method of formation of solution is given in Column I. Match it with the type of solution given in Column II.
Column I Column II
(i) Sulphur vapours passed through cold water (p) Normal electrolyte solution
(ii) Soap mixed with water above critical micelle concentration (q) Multi molecular colloids
critical micelle concentration
(iii) White of egg whipped with water (r) Associated colloid
(iv) Soap mixed with water below (s) Macro molecular colloids
critical micelle concentration

1. i-q, ii-r, iii-s, iv-p
2. i-p, ii-q, iii-r, iv-s
3. i-q, ii-p, iii-s, iv-r
4. i-r, ii-s, iii-q, iv-p

Q. Also known as the electro-dispersion method, the Bredig’s arc method applies a high voltage between two electrodes of a metal (like gold or silver) immersed in a dispersion medium to obtain a colloidal sol of the metal. Which of the following regarding the electrodes?

1. The electrodes are made of different metals
2. The electrodes are made of the same metals
3. The electrodes are kept very far apart
4. The electrodes are kept close to each other and the dispersion medium is cooled by a freezing mixture

Q. If blood plasma is precipitated, without using any equipment how will you convert precipitated blood into a colloid again?

1. Through dialysis
2. Through Bredic’s arc method
3. Through peptization
4. None the above

Q. When an excess of $AgN{O}_3$ is treated with $KI$ solution, $AgI$ forms a:

1. positively charged sol
2. negatively charged sol
3. neutral sol
4. true solution

Q. Match the following
$\begin{array}{cccc}& \text{Column I}& & \text{Column II}\\ & \text{(Method of preparation)}& & \text{(Type of sol)}\\ \text{a}& \text{Electrodispersion}& \text{p}& \text{Mercury sol}\\ \text{b}& \text{Mechanical dispersion}& \text{q}& \text{Hydrosol of gold}\\ \text{c}& \text{Ultrasonic method}& \text{r}& \text{Graphite sol}\\ \text{d}& \text{Peptisation}& \text{s}& \text{AgI sol}\end{array}$

1. $a\to q$; $b\to r$; $c\to s$; $d\to p$
2. $a\to r$; $b\to q$; $c\to p$; $d\to s$
3. $a\to r$; $b\to s$; $c\to p$; $d\to q$
4. $a\to q$; $b\to r$; $c\to p$; $d\to s$

Q. Assertion :Lyophilic sols are reversible sols. Reason: Lyophilic sols can be reconstituted by simply remixing the dispersed phase and dispersion medium.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect