Group 13 Elements

Group 13 Oxide Basicity

As we move down Group 13, the metallic character increases, and hence the electropositive character increases. As electropositivity increases, the basicity of the oxides increases.

The order of basicity for Group 13 oxides is .

Conclusion:

is the most basic oxide.

To solve this problem, we need to evaluate both the Assertion (A) and Reason (R) given in the question.

Assertion (A): Melting point of Boron (2453 K) is unusually high in group 13 elements.

Reason (R): Solid Boron has a very strong crystalline lattice.

1. First, let's examine the Assertion (A). Boron's melting point is indeed significantly higher compared to other group 13 elements, such as aluminum, gallium, indium, and thallium. This makes Assertion (A) a true statement.
2. Next, let's consider the Reason (R). Boron does form a very strong and complex three-dimensional covalent network structure, leading to a strong crystalline lattice. This crystalline structure is primarily responsible for its high melting point. Hence, Reason (R) is also a true statement.
3. Now, we need to determine if Reason (R) is the correct explanation for Assertion (A). The strong covalent lattice of boron contributes to its high melting point because breaking this extensive network of bonds requires a significant amount of energy. Therefore, Reason (R) indeed serves as a proper explanation for Assertion (A).

Given this logical analysis, both the assertion and the reason are correct, and the reason correctly explains the assertion.

The correct answer is: Both (A) and (R) are correct and (R) is the correct explanation of (A).

The given question involves the dissolution of a yellow compound of lead chromate in a hot NaOH solution, forming a lead complex. We'll solve the question step-by-step to identify the correct product.

Lead chromate ( ) is a yellow compound commonly used in paints and pigments. When treated with a hot sodium hydroxide ( ) solution, it reacts to form a lead complex. The possible options indicate different types of complexes.

Let's analyze the reaction:

1. when dissolved in , forms , which is a lead complex.
2. In this complex, the lead ion ( ) coordinates with hydroxide ions ( ) to form .
3. This complex is dianionic because it carries a -2 charge.
4. The lead atom is coordinated by four hydroxide ions, giving it a coordination number of four.

At this point, comparing the identified complex with the options given:

• The first option, "Tetraanionic complex with coordination number six," is incorrect since the lead complex formed is dianionic, not tetraanionic, and has a coordination number of four, not six.
• The second option, "Neutral complex with coordination number four," is incorrect because the complex is not neutral; it has a charge of -2.
• The fourth option, "Dianionic complex with coordination number four," is correct as it accurately describes the characteristics of the complex .
• The third option, "Dianionic complex with coordination number six," is incorrect because the coordination number is four, not six.

Therefore, the correct answer is: Dianionic complex with coordination number four.

This explanation shows how basic coordination chemistry and complex ion formation principles are applied to solve the problem.