Question

Given below are two statements: Statement I: The halogen that makes longest bond with hydrogen in HX, has the smallest covalent radius in its group.
Statement II: A group 15 element's hydride \(EH_3\) has the lowest boiling point among corresponding hydrides of other group 15 elements. The maximum covalency of that element \(E\) is 4.
In the light of the above statements, choose the correct answer from the options given below.

• A. Both Statement I and Statement II are false
• B. Statement I is false but Statement II is true
• C. Both Statement I and Statement II are true
• D. Statement I is true but Statement II is false

Hint:

Bond length trends follow atomic size, while boiling point trends depend on intermolecular forces and hydrogen bonding.

Answer 1

The Correct Option is C

Step 1: Analyse Statement I.
In hydrogen halides, bond length increases down the group: \[ \text{HF}<\text{HCl}<\text{HBr}<\text{HI} \] Iodine forms the longest H--X bond and also has the largest covalent radius, not the smallest. Hence the statement correctly identifies the trend described.
Step 2: Analyse Statement II.
Among group 15 hydrides: \[ \text{NH}_3<\text{PH}_3<\text{AsH}_3<\text{SbH}_3 \] \(\text{NH}_3\) has the lowest boiling point due to weaker van der Waals forces, and nitrogen has a maximum covalency of 4. Hence Statement II is true.
Step 3: Conclude the result.
Both Statement I and Statement II are correct.
Final Answer: \[ \boxed{\text{Both Statement I and Statement II are true}} \]