Electrical Properties of Colloids

Q.

What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?

Q.

The incorrect statement below regarding colloidal solutions is:

1. A colloidal solution shows colligative properties

2. An ordinary filter paper can stop the flow of colloidal particles

3. A colloidal solution shows the Brownian motion of colloidal particles

4. The flocculating power of ${\mathrm{Al}}^{3+}$is more than that of ${\mathrm{Na}}^{+}$

Q. During electro-osmosis of $Fe(OH{)}_3$ sol:

1. The sol particles move towards the anode
2. The sol particles move towards the cathode
3. The dispersion medium moves towards the anode
4. The dispersion medium moves towards the cathode

Q. Zeta potential ( or electrokinetic potential ) is the

1. potential required to bring about coagulation of a colloidal sol
2. potential required to give the particles a speed of 1 cm/ sec in the sol
3. potential difference between fixed charged layer and diffused layer having opposite charge
4. potential energy of colloidal particles

Q.

What is coagulation?

Q. When an excess of a very dilute aqueous solution of KI is added to a very dilute aqueous solution of silver nitrate, the colloidal particles of silver iodide are associated with which of the following Helmholtz double layer?

1. AgI ¦ Ag⁺ ¦ I^-
2. AgI ¦ K⁺ ¦ NO₃^-
3. AgI ¦ NO₃^- ¦ K⁺
4. AgI ¦ I^- ¦ K⁺

Q.

Standard electrode potential is a intensive property or extensive property ? Give reasons.

Q. Which of the following is the correct adsorpation isobar for physisorption?
Here, $\left(\frac{x}{m}\right)$ is extent of adsorption per unit mass of adsorbent.

1. 
2. 
3. 
4. 

Q. The potential at a point 0.1 m from an isolated point charge is +100volt.What will be the nature of point charge?

Q.

Explain the following terms :

1. Electrophoresis

2. Coagulation

3. Dialysis

4. Tyndall effect

Q. In conductometric titration of $AgN{O}_3$ with $KCl$ (titrant):

1. Conductivity sharply decreases until the equivalence point
2. Conductivity sharply increases until the equivalence point
3. After equivalence point, on addition of $KCl$, the conductivity increases sharply
4. After equivalence point, on addition of $KCl$, the conductivity remains constant

Q. Which of the following statement is not correct about physisorption ?

1. It is a reversible process.
2. Heat of adsorption is low, around $20-40kJmo{l}^{-1}$
3. It requires activation energy.
4. It decreases with increase in temperature.

Q. Write the reason for the stability of colloidal sols.

Q. The potential difference between the fixed charged layer and the diffused layer having opposite charges is known as:

1. Electrode potential
2. Streaming potential
3. Zeta potential
4. Electrochemical potential

Q. Buffer capacity is maximum when concentration of acid is same as concentration of salt in case of acidic buffer. Why?

Q.

Explain what is observed

When a beam of light is passed through a colloidal sol ?

An electrolyte, NaCl is added to hydrated ferric oxide sol ?

Electric current is passed through a colloidal sol ?

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

Q. Which of the following is correct adsorption isobar for chemisorption ?
Here,
$\left(\frac{x}{m}\right)$ is extent of adsorption per unit mass of adsorbent

1. 
2. 
3. 
4. 

Q. According to langmuir adsorption isotherm:
For adsorption of a gas over solid surface, rate of adsorption is proportional to:

1. Fraction of surface available for adsorption.
2. Pressure of gas
3. Both (a) and (b)
4. Fraction of surface covered on adsorbent.

Q. 8.Which of the following colloids contain gas as dispersed phase and solid as dispersion medium? A) face cream B) cheese C) pumice D) cod liver oil

Q.

The factors which are responsible for the stability of lyophilic sols are:

1. Charge and solvation of the colloidal particles

2. Charge of the colloidal particles

3. Size of the colloidal particles

4. Solvation of the colloidal particles

Q. 66. In acidic medium Mno2 is an oxidant as Mno2(s) +4H(+) +2e(-) gives Mn2+ + 2H20 If pH of the solution is decreased by one unit, the electrode potential of the half cell Pt:Mno2; Mn2+ will change by

Q. Which of the following substances gives a positively charged sol?

1. Gold
2. Arsenious sulphide
3. Starch
4. Ferric hydroxide

Q. The atoms of copper contain electrons and the atoms of rubber also contain electrons. Then why does copper conduct electricity but rubber doesnt conduct electricity ?

Q.

Gold number is associated with-

1. Electrophoresis

2. Purple of cassius

3. Protective colloid

4. Amount of pure gold

Q.

Does $\mathrm{Ecell}$ depends on concentrations?

Q.

Which one of the following is not represented by sols [MP PMT 1992]

1. Tyndall effect

2. Flocculation

3. Paramagnetism

4. Absorption

Q. Explain the following terms with suitable examples.
(i) cationic detergents
(ii) anionic detergents and
(iii) non-ionic detergents.

Q. Choose the correct statement(s) regarding adsorption of gases on solids:

1. The extent of adsorption of a gas depends on pressure of the gas.
2. The extent of adsorption of a gas does not depend on pressure of the gas.
3. As the temperature increases, adsorption is favoured.
4. As the temperature increases, desorption is favoured.

Q. The normality of a 500ml Ca(OH)2 solution which contain 9.033×10^22 hydroxide ions i