1. Select the correct statement among the given below.
a) All coking coals are caking but not all caking coals are coking
b) All caking coals are coking but not all coking coals are caking
c) Coking and caking are the same types of coals
d) All types of coals can be coked
Explanation: All coking coals are caking but not all caking coals are coking.Only that coal which has a tendency to soften, swell and stick together during strong heating in absence of air can be coked.
2. Coals which become soft, plastic and fuse together to form large coherent masses are called ______
a) caking coals
b) non-caking coals
c) non-coking coals
d) pulverized coal
Explanation: Coals which becomes soft, plastic and fuse together to form large coherent masses are called caking coals. Coals which undergo no fusing affects are called non-coking coals. Coking coals give hard, porous and strong residue after heating in absence of air.
3. When a coking coal is burnt in absent of air, hard, strong and porous residue left is called as _____
a) Coke
b) Ash
c) Caking coal
d) Non-coking coal
Explanation: When a coking coal is burnt in absent of air, hard, strong and porous residue left is called coke. Coke is white, lustrous, dense, porous and coherent mass
4. Which of the following is a secondary solid fuel?
a) Wood
b) Charcoal
c) Peat
d) Anthracite
Explanation: The fuels which are obtained from the solid fuels are called as secondary solid fuel. Charcoal is produced by the destructive distillation of wood. It is in the form of residue. Coke is also a secondary solid fuel.
5.By which type of coal does briquettes are made?
a) High grade fuel
b) Ultra high grade coal
c) Low grade fuel
d) High grade coal
Explanation: Briquettes are made by compressing low grade coal with or without binder (5-8% of coal tar or molasses). It helps us to utilize small-sized waste coal produced in mining and hence likely to be an important method as the best coal seems to get depleted.
6. How can we remove volatile matter form briquettes?
a) By baking them
b) By cooling them
c) By heating them
d) By applying some extra pressure
Explanation: The briquettes produced by mixing of the binder are baked to remove volatile matter present in it. Removing volatile matter from them will increase their calorific value to a certain point.
7. Which product is formed after the process of carbonisation?
a) Charcoal
b) Coal tar
c) Coal gas
d) Coke
Explanation: When the lignite coal is strongly heated out of contact with air, then coke is formed. Coke is used to smelt iron in the blast furnace process. It has the highest amount of carbon present in it
8. Which type of coal gets soften on heating?
a) Caking coal
b) Coking coal
c) Anthracite
d) Semi-bituminous
Explanation: On heating caking coal it gets soften producing a pasty mass which fuses together yielding coherent masses impervious to air. Coals that contains less pasty material are either non-caking or less caking in nature.
9. If the coke formed from the residue of the caking coal is hard, porous and strong then it is called coking coal.
a) True
b) False
Explanation: The so less caking material obtained from the caking coal is coke. All coking coals are caking coals but all caking coals are not coking coals.
10. Which of the following should be present in least amount, so as to give a good metallurgical coke?
a) Ash content
b) Moisture content
c) Volatile matter
d) Sulphur and phosphorous content
Explanation: Sulphur and phosphorous content in the coke can contaminate the metal and adversely affect its properties. They tend to make the metal brittle. Sulphur content should note be less than 0.5% and phosphorous 0.1%. Moisture should be less than 4% and ash content less than 6%.