250+ TOP MCQs on Inorganic Chemical – Phosphoric Acid and Answers

Chemical Industry Multiple Choice Questions on “Inorganic Chemical – Phosphoric Acid”.

1. Ortho phosphoric acid is completely miscible with water.
a) False
b) True

Answer: b
Clarification: Phosphoric acid is completely miscible with water at 42.6°C, as it mixes with water in all proportions at 42.6°C.

2. Which of the following is not a reaction of wet process method of production of phosphoric acid?
a) Ca3 (PO4)2 + 3H2SO4 + 6H2O → 2H3PO4 + 3(CaSO4·2H2O)
b) 6HF + SiO2 → H2 SiF6 + 2H2O
c) Ca3 (PO4)2 + 6HCl + 6H2O → 2H3PO4 + 3CaCl2
d) P2 O5 + 3H2O → 2H3PO4

Answer: d
Clarification: Reaction P2 O5 + 3H2O → 2H3PO4 takes place in electric furnace process, remaining reactions takes places in wet process method (both H2SO4 leaching and HCl leaching).

3. Which evaporator is used to concentrate the dilute acid produced in wet process method by H2SO4 leaching?
a) Single effect evaporator
b) Film evaporator
c) Triple effect evaporator
d) Circulation evaporator

Answer: a
Clarification: The dilute acid (phosphoric acid) produced in wet process by H2SO4 leaching method is concentrated in a single effect evaporator up to 50%. Most of it is converted into high concentration chemical fertilizer.

4. What temperature must be maintained in the reactor used in wet process by H2SO4 leaching?
a) 100°C
b) 80°C
c) 150°C
d) 120°C

Answer: b
Clarification: If the temperature is above 100°C, other products are formed which are difficult to filter. By adjusting the temperature to 80°C, gypsum is formed which can be easily filtered.

5. Which material is used in the construction of storage tanks in wet process by H2SO4 leaching?
a) PVC coated steel
b) Steel lined with acid proof brick
c) Stainless steel
d) Rubber lined steel

Answer: d
Clarification: Reaction tanks are made of Steel lined with acid proof brick. Filter is type 316 stainless steel. Storage tanks are made up of rubber lined steel. Air vent systems are made up of PVC coated steel.

6. Which is the economical process for manufacture of phosphoric acid in India?
a) Wet process by H2SO4 leaching
b) Wet process by HCl leaching
c) Electric furnace processes
d) Blast furnace process

Answer: b
Clarification: Wet process by HCl leaching is the economical process in India, because of excess chlorine and low sulfur content and we can produce ammonium sulfate from gypsum in H2SO4 process.

7. Which of the following is used as reducing agent in electric furnace process (direct conversion at plant site)?
a) Coke
b) Graphite
c) Nascent hydrogen
d) Sodium amalgam

Answer: a
Clarification: Coke is used as reducing agent for reducing phosphorous present in calcium phosphate Ca3 (PO4)2 into elemental phosphorous P4.

8. (H_3 PO_4 ,, ^{underrightarrow{1}} H_4 P_2 O_7 ,, ^{underrightarrow{1}} HPO_3) Indicate the temperatures 1and 2?
a) 1.300°C 2.1000°C
b) 1.250°C 2.900°C
c) 1.250°C 2.500°C
d) 1.100°C 2.1000°C

Answer: b
Clarification: Ortho phosphoric acid on heating to 250°C gives pyro phosphoric acid, which on further heating to 900°C produces meta phosphoric acid.

9. Which electrostatic precipitator element is used to resist free HF steel action?
a) Arsenic
b) Mercury
c) Graphite
d) Selenium

Answer: c
Clarification: To resist the action of free HF steel present, graphite is used as the electrostatic precipitator element.

10. Which solvent is used as make-up for the extraction of H3PO4 from CaCl2 solution?
a) Acetone
b) Benzene
c) Water
d) Amyl alcohol

Answer: d
Clarification: Butanol or amyl alcohol is generally used as make-up solvent for the extraction of H3PO4 from CaCl2 solution.

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