If the valency of $A$ is $3$ and $B$ is $2$,then the formula of the compound formed is:

The most common oxidation state of an element is $-2$. The number of electrons present in its outermost shell is

Predict the formulas of the stable binary compounds that would be formed by the combination of the following pairs of elements.
$(a)$ Lithium and oxygen
$(b)$ Magnesium and nitrogen
$(c)$ Aluminium and iodine
$(d)$ Silicon and oxygen
$(e)$ Phosphorus and fluorine
$(f)$ Element $71$ and fluorine

Which of the properties remains unchanged on descending a group in the periodic table?

An element $(A)$ occurs in the short period having electronic configuration $ns^2 np^1$. The formula of its oxide will be

What is the stock notation of Manganese dioxide?