Chemical Industry Multiple Choice Questions on “Inorganic Chemical – Graphite”.
1. Which of the following statements regarding graphite are wrong?
a) Graphite is a semi-metal
b) Graphite is a form of coal
c) Graphite is used as heat resistant material
d) Graphite is an amorphous allotrope of carbon
Answer: d
Clarification: Graphite is a crystalline allotrope of carbon, form of coal, a semi-metal, a high temperature lubricant, and corrosion and heat resistant material.
2. Which of the following is raw material used in manufacture of graphite is burned out and requires replacement?
a) Graphitized grade coke
b) Saw dust
c) Furnacing sand
d) Pitch binder
Answer: b
Clarification: Furnacing acid is repeatedly used for covering the reactants whereas saw dust used for final insulation cover is burned out and replacement is required.
3. What is the temperature at which coke is calcined in the manufacture of graphite?
a) 3000°C
b) 2000°C
c) 1400°C
d) 900°C
Answer: c
Clarification: Coke is calcined at 1400°C to evaporate impurities, mixed with pitch, made into shapes and sent to graphitizing furnace where the temperature is 3000°C.
4. What does a run require in manufacture of graphite?
a) 15-20 days of heating
b) 2-4 days of cooling
c) 1 day to load and unload
d) 1 day each to load and unload
Answer: d
Clarification: A run requires 2-4 days of heating, 1 day each to load and unload, and 15-20 days for cooling. After every run we must rebuilt the furnace side walls.
5. Charge forms the resistor in preparation of artificial graphite.
a) True
b) False
Answer: a
Clarification: Graphite is prepared in a rectangular shape electric resistance furnace in which charge forms the resistor. Furnace is built with loosely piled refractory brick on sides, concrete ends and floor with cooling pipes embedded.