Which of the following pairs has elements containing the same number of electrons in the outermost orbit?

In the long form of the periodic table,the $d$-block element which forms an interstitial hydride is

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

Which of the following sequences correctly represents the decreasing acidic nature of oxides?

Which one of the following orders correctly represents the increasing acid strengths of the given acids?

Statement $I :$ Acid strength increases in the order given as $HF < HCl < HBr < HI$.
Statement $II :$ As the size of the elements $F, Cl, Br, I$ increases down the group,the bond strength of $HF, HCl, HBr$ and $HI$ decreases and so the acid strength increases.
In the light of the above statements,choose the correct answer from the options given below.