Identify the correct order of basicity for the following oxides: $Na_2O, MgO, CuO, SiO_2$.

The chemical properties of $Li$ and $Mg$ are similar because:

The oxide of a metal $(R)$ can be reduced by the metal $(P)$,and metal $(R)$ can reduce the oxide of metal $(Q)$. Then the decreasing order of the reactivity of metals $(P)$,$(Q)$,and $(R)$ with oxygen is:

Which of the following gases can displace all other gases from a mixture?

Which is the strongest acid among the following?

Given below are two statements:
Statement $I$ : Both metal and non-metal exist in $p$ and $d-$block elements.
Statement $II$ : Non-metals have higher ionisation enthalpy and higher electronegativity than the metals.
In the light of the above statements,choose the most appropriate answer from the option given below: