1. Which of the following is denuding reaction?
a) NaCl+H2O →\(NaOH+\frac{1}{2} H_2+\frac{1}{2} Cl_2 \)
b) Cl– →\(\frac{1}{2}\) Cl2 + e–
c) Na + Hg →NaHg
d) NaHg+H2O →NaOH+\(\frac{1}{2}\) H2 + Hg
Explanation: Denuding reaction is the reaction of sodium amalgam with water, which on reacting produces sodium hydroxide, hydrogen, and mercury.
2. Major production of caustic soda is through ________________
a) Mercury cell process
b) Diaphragm cell process
c) Chemical process
d) Mebrane cell process
Explanation: 88% of total production is by mercury cell process, 7% by diaphragm cell process, 4% by membrane process, and 1% through chemical process.
3. Reagent used for drying of Cl2 is ______________
a) H3PO4
b) H2SO4
c) HCl
d) HNO3
Explanation: Minor quantities of NaOH and Na2CO3 are used for salt purification and sulfuric acid H2SO4 being dehydrating agent is used for drying of Cl2.
4. Concentration of NaOH produced in mercury cell process is ___________
a) 10-12%
b) 30-33%
c) 50%
d) 70%
Explanation: 10-12% NaOH is produced in diaphragm cell. 30-33% NaOH is produced by membrane process. 70% NaOH is produced in mercury cell process.
5. Which of the following is an advantage of mercury cell process?
a) Pure sodium hydroxide
b) Pure chlorine gas
c) Utilization of less pure brine
d) Low electrical energy consumption
Explanation: Advantages of mercury cell process are pure chlorine gas and pure 50% sodium hydroxide without evaporation. Pure sodium hydroxide is an advantage of membrane process. Utilization of less pure brine is an advantage of diaphragm cell process.
6. Which of the following is a disadvantage of membrane cell process?
a) Asbestos emission
b) Mercury contamination
c) High purity of brine
d) High electrical energy consumption
Explanation: Asbestos emission is a disadvantage of diaphragm cell process. Mercury contamination and High electrical energy consumption are disadvantages of mercury process. High purity of brine is a disadvantage of membrane cell process.
7. Pure sodium hydroxide is obtained in mercury cell process.
a) True
b) False
Explanation: The statement is false since pure chlorine gas and pure 50% sodium hydroxide without evaporation are obtained in mercury cell process whereas pure sodium hydroxide is obtained in membrane process.
8. Diaphragm used in diaphragm cell process is ______________
a) Asbestos
b) Poly vinyl chloride
c) Wooden material
d) Woven fabric
Explanation: Diaphragm cell is an electrolytic cell in which the anodic and cathodic liquors and products are separated by diaphragm made of asbestos.
9. Which of the following product is obtained at cathode in mercury cell process?
a) NaOH
b) NaHg
c) Cl2
d) NaCl
Explanation: NaCl is the electrolyte used, NaOH is the product obtained in denuding tower, Cl2 is product obtained at anode, and NaHg is the product obtained at cathode in mercury cell process.
10. Membrane used in membrane cell process is ______________
a) Asbestos
b) Anion- exchange membrane
c) Cation-exchange membrane
d) Woven fabric
Explanation: Membrane cell process uses Cation-exchange membrane since it separates anolyte and catholyte, and also prevents migration of chloride ions into catholyte.