Question

The correct statements from the following are:
(A) The decreasing order of atomic radii of group 13 elements is Tl $>$ In $>$ Ga $>$ Al $>$ B.
(B) Down the group 13 electronegativity decreases from top to bottom.
(C) Al dissolves in dil. HCl and liberate H$_2$, but conc. HNO$_3$ renders Al passive by forming a protective oxide layer on the surface.
(D) All elements of group 13 exhibits highly stable +1 oxidation state.
(E) Hybridisation of Al in [Al(H$_2$O)$_6$]$^{3+}$ ion is sp$^3$d$^2$.
Choose the correct answer from the options given below.

• A. (C) and (E) only
• B. (A), (C) and (E) only
• C. (A), (B), (C) and (E) only
• D. (A) and (C) only

Answer 1

The Correct Option is A

Step 1: Evaluate each statement
Statement (A):
The atomic radii order for group 13 elements is asserted as \(\text{Tl} > \text{In} > \text{Al} > \text{Ga} > \text{B}\), contradicting the actual order \(\text{Tl} > \text{In} > \text{Ga} > \text{Al} > \text{B}\).
- This statement is false.
2.Statement (B):  
Electronegativity generally decreases down a group. However, the presence of \(d\)-electrons in \(\text{Ga}\), \(\text{In}\), and \(\text{Tl}\) disrupts this simple trend in their electronegativity values.  
- This statement is false.
3.Statement (C):  
\(\text{Al}\) reacts with dilute \(\text{HCl}\) to produce \(\text{H}_2\):
\[2\text{Al} + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2.\]
Additionally, concentrated \(\text{HNO}_3\) passivates \(\text{Al}\) by forming an oxide layer, preventing further reaction.  
- This statement is true.
4.Statement (D):  
Within group 13, the \(+3\) oxidation state is more stable than \(+1\). The \(+1\) state is observed in \(\text{Tl}\) due to the inert pair effect, but it lacks significant stability across all elements in this group.  
- This statement is false.
5.Statement (E):
In \([\text{Al}(\text{H}_2\text{O})_6]^{3+}\), the hybridization of \(\text{Al}\) is \(\text{sp}^3\text{d}^2\), resulting in an octahedral geometry.  - This statement is true.
Step 2: Conclusion
Statements (C) and (E) are accurate.
Final Answer: (1).