In the reaction $2Br^- + X_2 \to Br_2 + 2X^-$,$X_2$ is .......

The periodic trend of chemical reactivity for alkali metals and halogens is described in the following statements. Which statement provides the correct concept?

Among $Al_2O_3$,$SiO_2$,$P_2O_3$,and $SO_2$,the correct order of acidic strength is:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A :$ Metallic character decreases and non-metallic character increases on moving from left to right in a period.
Reason $R :$ It is due to increase in ionisation enthalpy and decrease in electron gain enthalpy,when one moves from left to right in a period.
In the light of the above statements,choose the most appropriate answer from the options given below :

Identify the most acidic oxide among the following oxides based on their reaction.

The elements with the following atomic numbers belong to the same group: