Engineering Questions with Answers - Multiple Choice Questions
Chemical Industry MCQ’s – Inorganic Chemical – Phosphoric Acid
1 - Question
Ortho phosphoric acid is completely miscible with water.
a) False
b) True
View Answer
Explanation: Phosphoric acid is completely miscible with water at 42.6°C, as it mixes with water in all proportions at 42.6°C.
2 - Question
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
View Answer
Explanation: 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 - Question
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
View Answer
Explanation: 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 - Question
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
View Answer
Explanation: 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 - Question
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
View Answer
Explanation: 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 - Question
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
View Answer
Explanation: 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 - Question
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
View Answer
Explanation: Coke is used as reducing agent for reducing phosphorous present in calcium phosphate Ca3 (PO4)2 into elemental phosphorous P4.
8 - Question
H3PO41→H4P2O71→HPO3 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
View Answer
Explanation: Ortho phosphoric acid on heating to 250°C gives pyro phosphoric acid, which on further heating to 900°C produces meta phosphoric acid.
9 - Question
Which electrostatic precipitator element is used to resist free HF steel action?
a) Arsenic
b) Mercury
c) Graphite
d) Selenium
View Answer
Explanation: To resist the action of free HF steel present, graphite is used as the electrostatic precipitator element.
10 - Question
Which solvent is used as make-up for the extraction of H3PO4 from CaCl2 solution?
a) Acetone
b) Benzene
c) Water
d) Amyl alcohol
View Answer
Explanation: Butanol or amyl alcohol is generally used as make-up solvent for the extraction of H3PO4 from CaCl2 solution.