Hydrides - Ionic, Covalent & Metallic - UNSOLVED PRACTICE SET
Chapter: Hydrogen | Topic: Hydrides Ionic Covalent Metallic
HYDRIDES - IONIC, COVALENT & METALLIC - UNSOLVED PRACTICE SET
Topic: Hydrides Ionic Covalent Metallic
Multiple Choice Questions
Q1. Ionic hydrides are formed by:
- Transition metals
- p-block elements
- s-block elements (except Be and Mg)
- Noble gases
Q2. Which of the following is a covalent hydride?
- NaH
- CaH₂
- CH₄
- TiH₂
Q3. Metallic hydrides are characterised by:
- Definite stoichiometry
- Non-stoichiometric composition
- High ionic character
- Insolubility in all solvents
Q4. The hydride ion (H⁻) is found in:
- NH₃
- HCl
- NaH
- CH₄
Q5. Which hydride is likely to be polymeric in nature?
- BeH₂
- NaH
- H₂S
- PdH₀.₆
Q6. Covalent hydrides are generally:
- Solid at room temperature with high melting points
- Volatile liquids or gases with low melting points
- Good conductors of electricity
- Always ionic in nature
Short Answer Questions
Q7. Classify the following hydrides as ionic, covalent, or metallic: NaH, H₂O, TiH₁.₇, CaH₂, NH₃, PdH₀.₅.
Q8. Why are ionic hydrides called "saline hydrides"? Write the reaction of NaH with water.
Q9. Explain why BeH₂ and MgH₂ are not purely ionic like NaH or CaH₂, despite being formed by s-block elements.
Q10. Metallic hydrides are used for hydrogen storage. Why is this possible? What is special about their structure?
Q11. Your school lab has samples of NaH and CH₄. Suggest two simple tests you could perform to distinguish between an ionic hydride and a covalent hydride.
Q12. Why do metallic hydrides have variable composition (non-stoichiometric)? Explain with reference to the nature of metallic bonding.
Long Answer Questions
Q13. Compare ionic, covalent, and metallic hydrides under the following headings:
(a) Nature of bonding
(b) Physical state and appearance
(c) Electrical conductivity
(d) Reaction with water
Give one example of each type.
Q14. Discuss the nature of hydrides formed by:
(a) s-block elements (Groups 1 and 2)
(b) p-block elements
(c) d-block and f-block elements
Explain the trend in the nature of hydrides across a period with examples.
Q15. Hydrogen storage is a major challenge for hydrogen-powered vehicles in India. Metallic hydrides like LaNi₅H₆ and TiFeH₂ are being researched for this purpose. Explain:
(a) How these metallic hydrides store hydrogen
(b) The advantage of using metallic hydrides over compressed hydrogen gas
(c) One challenge that needs to be overcome for practical use
Numerical / Application-Based Problems
Q16. A sample of a metallic hydride has the formula TiFeH₁.₉₅. The molar mass of TiFe is 103.7 g/mol.
(a) Calculate the mass percentage of hydrogen in this hydride.
(b) If 100 g of this hydride is used, how many grams of hydrogen can be released?
(c) Compare this hydrogen storage capacity with 100 g of liquid hydrogen (which is 100% hydrogen by mass). What is the disadvantage?
Q17. Ionic hydride NaH reacts with water according to the equation: NaH + H₂O → NaOH + H₂
(a) Calculate the mass of NaH required to produce 11.2 L of H₂ gas at STP.
(b) Calculate the mass of NaOH formed in the reaction.
(c) If the NaOH solution is diluted to 500 mL, what is the molarity of the resulting solution?
[Given: Atomic masses: Na = 23 u, H = 1 u, O = 16 u; Molar volume at STP = 22.4 L]
Q18. A hydrogen storage tank for a bus in Delhi uses LaNi₅H₆, which can release hydrogen upon heating. The density of LaNi₅H₆ is 8.2 g/cm³.
(a) Calculate the molar mass of LaNi₅H₆. [Atomic masses: La = 139, Ni = 59, H = 1]
(b) Calculate the mass of hydrogen stored in 1 litre (1000 cm³) of LaNi₅H₆.
(c) At STP, what volume would this hydrogen occupy?
[Molar volume at STP = 22.4 L]