Give chemical name and nature (acidic or basic) of the ash formed by burning of a $Mg$ ribbon in the air?

The correct option is D magnesium oxide, basic

Option $\left(D\right)$ is correct.

Magnesium oxide is formed as ash by burning of $Mg$ ribbon in the air. This is an exothermic reaction.

$2Mg+O_2\to 2MgO+energy$

Magnesium oxide is basic in nature as it reacts with water to form magnesium hydroxide which is a base.