This set of Class 11 Chemistry Chapter 9 Multiple Choice Questions & Answers (MCQs) focuses on “Properties of Dihydrogen”.
1. Which of the following is not a property of dihydrogen?
d) heavier than air
Explanation: Physical properties of dihydrogen include that it is colourless, odourless, tasteless, combustible gas. It is lighter than air and insoluble in water and is also neutral to Litmus. Therefore heavier than air is not a property of dihydrogen.
2. Dihydrogen is relatively inert at room temperature.
Explanation: The inertness of dihydrogen comparatively at 27 degree-celcius, is because of its high bond energy of the hydrogen bond. Therefore we can say the reactions involving dihydrogen occur at high temperatures only.
3. At high electric discharge hydrogen and oxygen combine to form _____________
c) hydrogen peroxide
Explanation: At 970 Kelvin, an electric discharge 2 moles of hydrogen molecule combines with one mole of Oxygen in order to form 2 moles of water. This has an enthalpy change of about 285.9 KJ/mol, the enthalpy change is negative for the above process.
4. Which of the following statement is true regarding the order of reactivity of halogens?
a) Fluorine’s reactivity is greater than that of bromine
b) Florine’s reactivity is greater than that of fluorine
c) Iodine’s reactivity is greater than that of chlorine
d) Bromine’s reactivity is greater than that of chlorine
Explanation: The order of reactivity of halogens with hydrogen is that Fluorine’s reactivity is greater than that of chlorine and chlorine’s reactivity is greater than that of bromine and bromine’s reactivity is greater than that of Iodine.
5. What is the temperature required in presence of molybdenum and iron for nitrogen to combine with hydrogen?
a) 123 Kelvin
b) 273 Kelvin
c) 673 Kelvin
d) 473 Kelvin
Explanation: At 673 Kelvin and 200 atmospheric pressure, one mole of nitrogen combines with three moles of hydrogen in presence of iron and molybdenum in order to form 2 moles of ammonia and the enthalpy change is 92.6 KJ per Mol, the enthalpy here change is negative.
6. Sodium and hydrogen combine to form sodium hydride in presence of heat, what is the oxidising agent here?
Explanation: In the formation of 2 moles of sodium hydride from two moles of sodium and one mole of hydrogen, the hydrogen acts as an oxidising agent. An oxidizing agent gains electrons from the other molecule and reduces itself.
7. How does vegetable oil gets converted into vegetable ghee?
Explanation: In presence of Nickel, as a catalyst at the temperature of 400 degrees Kelvin, vegetable oil is converted into vegetable ghee in presence of hydrogen and this process of transformation of oil into ghee is known as hydrogenation.
8. Hydrogen is used in the manufacture of _____
a) carbon dioxide
c) nitrogen dioxide
Explanation: In the presence of Cobalt, one mole of carbon monoxide in gaseous state combines with 2 moles of the hydrogen molecule in a gaseous state in order to form one mole of methanol in a liquid state. Hydrogen is used in the manufacture of methanol.
9. Hydrogen is used in an oxyhydrogen flame.
Explanation: Hydrogen is used to produce a temperature of 2850 degrees centigrade and the oxygen atomic hydrogen flame produces a temperature of 4000-degree centigrade, so it is used in an oxyhydrogen flame. So the above statement is true.
10. Is hydrogen used in the synthesis of ammonia?
a) cannot say
d) not at all
Explanation: The largest single use of dihydrogen is that it is used in the synthesis of ammonia which is used in the manufacture of nitric acid and also fertilizers, so there is an indirect use of hydrogen in the synthesis of fertilizers.
11. Manufacture of synthetic petrol involves _____________
Explanation: Hydrogen is used in the manufacture of synthetic petrol, that is why heating dihydrogen with coal and heavy oils under the very high pressure and presence of catalyst we can manufacture synthetic petrol.
12. Which of the following is true regarding the uses of hydrogen?
a) it is used in the manufacture of synthetic petrol
b) it is used as an oxidizing agent in the extraction of metals
c) it is used in a fuel cell for generating mechanical energy
d) it is used as rocket fuel in its gaseous form
Explanation: The correct statement of the incorrect statements are; the dihydrogen is used as a reducing agent in the extraction of metals, it is used in a fuel cell for generating electrical energy and liquid hydrogen is used as rocket fuel.
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