Chemistry - Study Mode

[#1086] The quality of petrol is expressed in terms of
Correct Answer

(C) Octane number

Explanation

Solution: Ignition quality of petrol is expressed by octane number and that of diesel by cetane number.

[#1087] Which of the following type of coal has the lowest proportion of volatile matter ?
Correct Answer

(D) Anthracite

Explanation

Solution: Anthracite has the lowest proportion of volatile matter.

[#1088] Brass contains
Correct Answer

(A) Copper and Zinc

Explanation

Solution: Brass is an alloy made of copper and zinc

the proportions of zinc and copper can be varied to create a range of brasses with varying properties. By comparison, bronze is principally an alloy of copper and tin.

[#1089] Among the fuels given below, the one with highest calorific value is
Correct Answer

(D) Natural gas

Explanation

Solution: The calorific values of different fuels (in Kcal/kg) in dry state are: Wood: 3500

Coal: 4000-7000

Coke: 6500

and Natural Gas: 8600 Kcal/kg.

[#1090] Which of the following is the best fuel in terms of energy released per gram of fuel?
Correct Answer

(A) Hydrogen

Explanation

Solution: The amount of energy released increases with the number of bonds present in the chemical substance or fuel. That is because each bond has a certain amount of energy stored in it therefore the more bonds the more energy is stored and more energy is released if these bonds break through combustion. Theoretical values of energy released per gram of fuel (in joules/ gram) are: Hydrogen: 142.5 KJ/g

Methane: 55.6 KJ/ g

Ethanol: 29.7 KJ/g

Butane: 49.6KJ/g.