Q1. Which of the following is the best method for the large-scale preparation of dihydrogen?
A) Electrolysis of water
B) Lane’s process
C) Bosch process
D) Wurtz reaction
Answer: C) Bosch process
Explanation: The Bosch process is widely used for the large-scale industrial production of hydrogen. It involves the reaction of water vapor with hot carbon (usually coke) to produce hydrogen and carbon monoxide, followed by the water-gas shift reaction to increase the hydrogen yield.
Q2. What is the main impurity found in dihydrogen obtained by the electrolysis of water?
A) Carbon dioxide
B) Nitrogen
C) Oxygen
D) Sulphur dioxide
Answer: C) Oxygen
Explanation: During the electrolysis of water, hydrogen is produced at the cathode, while oxygen is released at the anode. Some oxygen may remain as an impurity in the dihydrogen produced, which needs to be purified before use.
Q3. The reaction of sodium with cold water produces which gas?
A) Oxygen
B) Hydrogen
C) Carbon dioxide
D) Nitrogen
Answer: B) Hydrogen
Explanation: When sodium reacts with cold water, sodium hydroxide (NaOH) and hydrogen gas (H₂) are formed. This is a typical method for the laboratory preparation of hydrogen using alkali metals.
Q4. Which of the following statements is NOT correct regarding hydrogen?
A) Hydrogen has the highest calorific value.
B) Hydrogen is a good conductor of electricity.
C) Hydrogen is highly flammable.
D) Hydrogen is the lightest element.
Answer: B) Hydrogen is a good conductor of electricity.
Explanation: Hydrogen, in its molecular form (H₂), is a poor conductor of electricity. It is a neutral molecule and does not have free electrons or ions to conduct an electric current.
Q5. The most abundant isotope of hydrogen in nature is:
A) Protium
B) Deuterium
C) Tritium
D) None of these
Answer: A) Protium
Explanation: Protium (¹H) is the most common isotope of hydrogen, comprising about 99.98% of the hydrogen found in nature. It has only one proton and no neutrons.
Q6. Hydrogen does not form which type of compound?
A) Ionic compounds
B) Covalent compounds
C) Interstitial compounds
D) Complex compounds
Answer: A) Ionic compounds
Explanation: Hydrogen typically forms covalent bonds by sharing electrons. However, it can form ionic bonds under certain conditions, such as with highly electronegative elements like halogens, but it does not commonly form typical ionic compounds.
Q7. Which of the following metals does not react with cold water to produce hydrogen gas?
A) Sodium
B) Magnesium
C) Calcium
D) Iron
Answer: D) Iron
Explanation: Iron does not react with cold water to produce hydrogen. It only reacts with steam at high temperatures, forming iron oxide and releasing hydrogen.
Q8. What is the oxidation state of hydrogen in NaH (sodium hydride)?
A) +1
B) -1
C) 0
D) +2
Answer: B) -1
Explanation: In metal hydrides like NaH, hydrogen has an oxidation state of -1. Sodium, being more electropositive, donates its electron to hydrogen.
Q9. Which of the following reactions is used in the preparation of hydrogen by the water-gas shift reaction?
A) CO + H₂O → CO₂ + H₂
B) CH₄ + H₂O → CO + 3H₂
C) H₂O + C → CO + H₂
D) H₂O₂ → H₂ + O₂
Answer: A) CO + H₂O → CO₂ + H₂
Explanation: The water-gas shift reaction is used to increase the yield of hydrogen by reacting carbon monoxide (CO) with water (H₂O) to produce carbon dioxide (CO₂) and hydrogen (H₂).
Q10. Which of the following reactions illustrates the reducing property of hydrogen?
A) H₂ + Cl₂ → 2HCl
B) H₂ + CuO → Cu + H₂O
C) H₂ + O₂ → H₂O
D) H₂ + N₂ → NH₃
Answer: B) H₂ + CuO → Cu + H₂O
Explanation: In this reaction, hydrogen reduces copper(II) oxide (CuO) to metallic copper (Cu), demonstrating its reducing property.
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