Species Na⁺Mg²⁺Al³⁺Si⁴⁺
Protons 11 12 13 14
Electrons 10 10 10 10
Size of isoelectronic cations decreases with increase in magnitude of nuclear charge
∴Order of decreasing size is Na⁺>Mg²⁺>Al³⁺>Si⁴⁺

Arsenic is the only metalloid among the given options.Its small amounts are even very harmful for humans

The acidic character of non metal oxides increases acrossa period from left to right and decreases down a group.So, acidic character will follow the order:oxide of nitrogen > oxides of sulfur > oxides of carbon.Among oxides of carbon acidic character increases withthe oxidation number of carbon. So, ⁺⁴CO ₂ is moreacidic than CO. Hence thesequence of acidic characteris N₂O⁵> SO₂> CO₂> CO

According to the general trend of I.E. in a period,it is expected that oxygen atom has higher I.E. than nitrogenatom but nitrogen atom has more stable half filled p-orbitals due to which it has higher I.E. than oxygenatom.

They are isoelectronic species.
N^3– O^2- Na⁺ F^-
No. of electrons 10 10 10 10
No. of protons 7 8 11 9
∴Attractive forces are highest in Na⁺.
∴Na⁺ is smallest in size.

Ionisation potential increases while moving in a period.
Group V VI VII VIII
Element N O F Ne
Oxygen (group 6) has low ionisation potential than N(group 5) because of stable configuration of nitrogen(half filled p-orbital)

While moving down in a group, effective nuclear attraction decreases due to addition of new orbits. As a result ionisation potential decreases. Hence, the correct order is Li > K > Cs.

While moving down in a group, effective nuclear attraction decreases due to addition of new orbits. As a result ionisation potential decreases. Hence, the correct order is Li > K > Cs.

A cation is always smaller in size as compared to corresponding neutral atom. Greater the magnitude of charge, smaller will be size of ion. Following is the correct order of decreasing size Al³⁺< Al²⁺< Al⁺< Al. ∴Al has largest size

Basicity of oxides decreases in a period and increases in a group.
∴SnO₂, Al₂O₃ and ZnO are amphoteric oxides.