Question

Element X is the lightest element of group 7 of periodic table which forms oxo-anion in +6 oxidation state. The colour of potassium salt of the oxo-anion is:

• A. Green
• B. Orange
• C. Yellow
• D. Brown

Hint:

Do not confuse manganate (green) with permanganate (purple).

Answer 1

The Correct Option is A

Element X is the lightest element of Group 7 in the periodic table that forms an oxo-anion in the +6 oxidation state. In Group 7, the elements are manganese (Mn), technetium (Tc), rhenium (Re), and bohrium (Bh). Out of these, manganese is the lightest element.

Manganese (Mn) forms several oxo-anions, but the most common in a +6 oxidation state is the manganate ion, \( \text{MnO}_4^{2-} \).

Now, when we consider potassium salt of the manganate ion, we have potassium manganate, \( \text{K}_2\text{MnO}_4 \).

Potassium manganate is known for having a distinct green color.

Thus, based on the relationship between the properties of manganese and its compounds, the color of the potassium salt of the oxo-anion of the lightest element in Group 7 is:

Green

Therefore, the correct option is:

• Green

The other options are incorrect because:

• Orange, yellow, and brown are not characteristics of potassium manganate, but they could relate to other manganese compounds in different oxidation states such as permanganates (\( \text{MnO}_4^- \)) which are purple.