Consider the following elements.

Which of the following is/are true about $$\mathrm{A}^{\prime}, \mathrm{B}^{\prime}, \mathrm{C}^{\prime}$$ and $$\mathrm{D}^{\prime}$$ ?

A. Order of atomic radii: $$\mathrm{B}^{\prime}<\mathrm{A}^{\prime}<\mathrm{D}^{\prime}<\mathrm{C}^{\prime}$$

B. Order of metallic character: $$\mathrm{B}^{\prime}<\mathrm{A}^{\prime}<\mathrm{D}^{\prime}<\mathrm{C}^{\prime}$$

C. Size of the element: $$\mathrm{D}^{\prime}<\mathrm{C}^{\prime}<\mathrm{B}^{\prime}<\mathrm{A}^{\prime}$$

D. Order of ionic radii: $$\mathrm{B}^{\prime+}<\mathrm{A}^{1^{+}}<\mathrm{D}^{\prime+}<\mathrm{C}^{+}$$

Choose the correct answer from the options given below :

The correct sequence of electron gain enthalpy of the elements listed below is

A. Ar

B. Br

C. F

D. S

Choose the most appropriate from the options given below:

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R:

Assertion A: $$\mathrm{H}_2 \mathrm{Te}$$ is more acidic than $$\mathrm{H}_2 \mathrm{~S}$$.

Reason R: Bond dissociation enthalpy of $$\mathrm{H}_2 \mathrm{Te}$$ is lower than $$\mathrm{H}_2 \mathrm{~S}$$.

In the light of the above statements, choose the most appropriate from the options given below:

Given below are two statements:

Statement - I: Along the period, the chemical reactivity of the elements gradually increases from group 1 to group 18 .

Statement - II: The nature of oxides formed by group 1 elements is basic while that of group 17 elements is acidic.

In the light of the above statements, choose the most appropriate from the options given below: