The elements with atomic number 2, I 0, 18, 36,
54 and 86 are all

Read carefully the following statements regarding the ions ${\mathrm{Na}}^{+}, {\mathrm{Mg}}^{2+},{\mathrm{F}}^{-}\mathrm{and} {\mathrm{O}}^{2-}$.

(I) All ions have the same number of valence electrons.
(II) All ions belong to the elements of the same period of the periodic table.
(III) All ions have the same electronic configuration.
(IV) All ions have the same number of electron shells.

Manya, Kartik, Gurnoor and Sheena had arranged the ions ${\mathrm{F}}^{-}, {\mathrm{Na}}^{+}, {\mathrm{O}}^{2-}$ and ${\mathrm{Mg}}^{2+}$ in decreasing orders of their ionic radii.

Manya - ${\mathrm{O}}^{2-}>{\mathrm{Mg}}^{2+}>{\mathrm{F}}^{-} >{\mathrm{Na}}^{+}$

Kartik - ${\mathrm{Mg}}^{2+}>{\mathrm{Na}}^{+}> {\mathrm{O}}^{2-}>{\mathrm{F}}^{-}$

Gurnoor - ${\mathrm{O}}^{2-}>{\mathrm{F}}^{-}>{\mathrm{Na}}^{+}>{\mathrm{Mg}}^{2+}$

Sheena - ${\mathrm{F}}^{-}> {\mathrm{Na}}^{+}>{\mathrm{O}}^{2-}> {\mathrm{Mg}}^{2+}$

Who had provided the correct order of their decreasing ionic radii? 

Which set of given elements A, B, C, D, E with atomic numbers 1, 3, 7, 10, 11 belongs to the same period and same group respectively.

Which of the following statements about the modern periodic table is/are incorrect?

1. The elements in the modern periodic table are arranged on the basis of their decreasing atomic number. 

2. The elements in the modern periodic table are arranged on the basis of their increasing atomic masses. 

3. Isotopes are arranged in adjoining or different group(s) in the modern periodic table. 

4. The elements in the modern periodic table are arranged on the basis of their increasing atomic number

Which of the following is true about the two substances?

Statement- I: Ordinarily ${\mathrm{H}}_2\mathrm{S}$ is a gas and ${\mathrm{H}}_2\mathrm{O}$ liquid.

Statement- II: Sulphur is more electronegative so that it forms a hydrogen bond.

Among $\mathrm{Mg}, {\mathrm{Mg}}^{2+}, \mathrm{Al}, {\mathrm{Al}}^{3+}$which will have the largest and smallest size respectively?