Chemistry NCERT Exemplar Solutions Class 11th Chapter Three

This is a Short Answer Type Questions as classified in NCERT Exemplar

Exothermic reaction- The reaction in which heat is released

For example- CaO + CO₂ → CaCO₃ + Heat

Endothermic reaction- The reaction in which heat is absorbed.

For example- 2NH₃ + heat → N₂ +3H₂

This is a Short Answer Type Questions as classified in NCERT Exemplar

The electronic configuration of Na is [Ne]3s¹ while that of Mg is [Ne]3s² as Mg possesses a fully filled 3s orbital thus its first ionisation enthalpy is higher than that of Na.

After losing one electron Na obtained the electronic configuration of Ne while Mg acquired the electronic configuration of Na thus the second ionisation energy of Na is higher than that of Mg.

This is a Short Answer Type Questions as classified in NCERT Exemplar

In the p block, some elements are metallic some elements are non-metallic while some elements are metalloids in nature. The oxides of metals are basic in nature and that of oxides of nonmetals are acidic in nature.

Acidic oxide SO₂ + H₂O →H₂SO₃

Basic oxide  Tl₂O + 2HCl → 2TlCl +H₂O

Amphoteric oxide

Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O

Al₂O₃ +2 NaOH → 2NaAlO₂ + H₂O

Reaction with water

B₃O₂ +3H₂O → 2H₃BO₃

P₄O₁₁  + 6H2O  → 4H₄PO₃

Cl₂ O₇ + H2O → HClO₄

This is a Short Answer Type Questions as classified in NCERT Exemplar

The anomalous behaviour of the first member of each group of representative elements i.e. of second period can be attributed to their small size, high charge/radius ratio, high electronegativity and absence of vacant d-orbitals to expand their oxidation state.The first member of each group of p-Block elements displays their greater ability to form multiple bond with itself, e.g. C=C, O=O, N=N and to other second periodic elements, e.g. C=O, C=N, N=N.

This is a Short Answer Type Questions as classified in NCERT Exemplar

The N possesses a half filled p-orbital which provides it extra stability due to symmetry due to which its electron gain enthalpy is positive and its ionization enthalpy is larger than that of O.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Option (i)

As across the period the atomic radius decreases due to the increase of effective nuclear charge.

This is a Short Answer Type Questions as classified in NCERT Exemplar

The characteristics properties of p-block elements are as follows:-

(i) It contain metals, nonmetals and metalloids

(ii) Mostly involved in covalent bonding

(iii) Some elements show variable oxidation state

(iv) It possesses relatively higher ionization enthalpy compared to the s-block elements.

This is a Short Answer Type Questions as classified in NCERT Exemplar

(i) C has the highest ionization energy among the given elements as along the period ionization enthalpy increases whereas it decreases down the group.

(ii) Al is the most metallic element among the given elements because down the group metallic character increases

This is a Short Answer Type Questions as classified in NCERT Exemplar