Hydrogen MCQ Quiz - Multiple Choice Questions & Answers Page 3

21. What is the most common element in the world?

1. Hydrogen
2. Oxygen
3. Helium
4. Carbon

22. What is the only by-product of hydrogen fuel-cells?

1. Carbon Dioxide (CO₂, which is a greenhouse gas)
2. Nothing
3. Water vapor
4. Helium

23. What is the strength of 20 volume solution of H^2O2?

1. 5g/L
2. 10g/L
3. 30g/L
4. 60g/L

24. When MnO^{4 reacts with H2O2 in basic medium then following species are involved, except}

1. MnO²
2. O²
3. OH^-
4. Mn²⁺

25. When sodium peroxide is treated with dilute sulphuric acid, we get

1. sodium sulphate and water
2. sodium sulphate and oxygen
3. sodium sulphate, hydrogen and oxygen
4. sodium sulphate and hydrogen peroxide

26. Which group forms hydride?

1. 6
2. 7
3. 8
4. 9

27. Which of the following compounds is used for water softening?

1. Ca₃ (PO₄)₂
2. Na₃PO₄
3. Na₆P₆O₁₈
4. Na₂HPO₄

28. Which of the following hydrides is electron-precise hydride?

1. B₂H₆
2. NH₃
3. H₂O
4. CH₄

29. Which of the following ions will cause hardness in water sample?

1. Ca²⁺
2. Na⁺
3. Cl^-
4. K⁺

30. Which one is ionic hydride in nature?

1. CrH
2. NH³
3. H^2O
4. NaH