Question

Given below are two statements:
Statement I: $\text{Al(OH)}^{2+}$ ion is predominant in soil between pH 4.7 & 6.5
Statement II: $\text{Al}^{3+}$ ion is predominant in soil pH below 4.7
In light of the above statements, choose the correct answer from the options given below:

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

Hint:

Soluble aluminum speciation and pH:
$\text{pH} < 4.7 \rightarrow \text{Al}^{3+}$ (highly toxic)
$\text{pH } 4.7 - 6.5 \rightarrow \text{Al(OH)}^{2+}$ and $\text{Al(OH)}_2^+$
$\text{pH} > 6.5 \rightarrow \text{Al(OH)}_3$ (insoluble precipitate)

Answer 1

The Correct Option is A