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

Which of the following is the correct order of acidic strength?

In which of the following are the oxides of three elements $X, Y$ and $Z$ correctly arranged in the increasing order of acidic nature? The electronic configurations of $X, Y$ and $Z$ are $[Ne] 3s^2 3p^1$,$[Ne] 3s^2 3p^5$,and $[Ne] 3s^2$ respectively.

The correct order of the non-metallic character among the elements $B, C, N, F$ and $Si$ is

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.

Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture?