250+ TOP MCQs on Inorganic Chemical – Cement and Lime and Answers

Chemical Industry Multiple Choice Questions on “Inorganic Chemical – Cement and Lime”.

1. Which type of cement is used for brick mortar composition?
a) Portland cement
b) High alumina
c) Hydraulic lime
d) Pozzolana

Answer: c
Clarification: Hydraulic lime is used only for brick mortar composition, low price and strength. Pozzolana cement is mixture of volcanic ash, burnt clay or shale in 2-4 parts with hydrated lime.

2. Which type of cement is manufactured by fusing limestone and bauxite?
a) Regular type portland cement
b) High alumina
c) Magnesium oxychloride
d) Portland cement

Answer: b
Clarification: High alumina cement is manufactured by fusing limestone’s and bauxite; rapid rate of high strength development to high values but with high heat rate liberation; superior resistance to sea and sulphate waters.

3. Which unit operation mentioned below is not involved in cement rock beneficiation?
a) Grinding
b) Flotation
c) Thickening
d) Compression

Answer: d
Clarification: The unit operations which are involved in cement beneficiation are grinding, classification, flotation, thickening etc. Rock is wet-ground, fed to a hydro separator where the overflow goes directly to the final thickener.

4. Why cement beneficiation is done?
a) To remove silica and iron content
b) To remove silica and aluminum content
c) To remove silica and sulfur content
d) To remove silica and magnesium content

Answer: a
Clarification: Much of the locally available limestone has too high a silica and iron content for direct use in cement manufacture. These undesirable constituents can be removed by ore dressing or beneficiation methods which are based on fluid mechanics and adsorption.

5. Why dry grinding process is preferred in the Portland cement production?
a) Savings in heat
b) High pressure
c) High grade
d) Low pressure

Answer: a
Clarification: Dry grinding process is predominant than wet grinding process because of savings in heat (less water to evaporate) and accurate control is possible. The sequence may include rough crushing.

6. Which lime has this criteria- Calcium>90%CaO?
a) Slaked lime
b) Hydraulic lime
c) Quicklime
d) Only lime

Answer: c
Clarification: Quicklime: high calcium(>90% CaO); low magnesium (5-25% MgO), dolomitic (25-40% MgO). Hydraulic lime and slaked lime contain Ca(OH)² and MgO-Mg(OH)² in varying percentage.

7. Which raw material is used in the hydrated lime process?
a) Quicklime
b) Limestone
c) Coal
d) Gypsum

Answer: a
Clarification: Pure quicklime is used as raw material in hydrated lime process. Quicklime lump, crushed to 2 cm or less, is added along with water or steam to a vertical cylindrical pug mill containing 18-24 extended horizontal arms.

8. CaO(s) + H₂O -> Ca(OH)² -where this chemical reaction occur?
a) Calcination limestone
b) Portland cement production
c) Cement rock beneficiation
d) Hydrated lime

Answer: d
Clarification: In hydrated lime process, quicklime reacts with water and the product from this complete reaction is light, dry slaked lime which is classified by screen or air separators to remove any overburned lime that did not hydrated.

9. Which one mentioned below is not a raw material used in the Portland cement production?
a) Clay
b) Limestone
c) Gypsum
d) Quicklime

Answer: d
Clarification: Quantitative requirements of Portland cement production are- clay-0.1 to 0.3 ton, limestone 1.2to1.3 tone, gypsum- 0.03 to 0.05, coal-0.25 to 0.40 and water is 3 tons required.