Chemistry

This is a short answer type question as classified in NCERT Exemplar

Hydrogen has electronic configuration 1s¹. On the one hand, its electronic configuration is similar to that of alkali metals in the first group of the periodic table, which have an outer electronic configuration (ns¹). As a result, hydrogen resembles alkali metals that lose one electron to become unipositive ions.

This is a short answer type question as classified in NCERT Exemplar

(i) The given compound is H₂O₂.

(ii) Textiles, paper pulp, leather, oils, fats, and other products use it as a bleaching agent. In both acidic and alkaline media, it works as an oxidising and reducing agent. It is therefore kept in dark wax-lined glass or plastic containers. As a stabiliser, urea might be used. It is kept away from dust since dust can cause the compound to decompose explosively.

This is a Matching Type Questions as classified in NCERT Exemplar

Ans: (i) → (b); (ii) → (d); (iii) → (c); (iv) → (a).

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: options (i) and (iv)

Ice and water are in equilibrium only at particular temperature and pressure. For any pure substance at atmospheric pressure, the temperature at which the solid and liquid phases are at equilibrium is called the normal melting point or normal freezing point of the substance. For example, it is 4°C in case of water. The system here is in dynamic equilibrium.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans:, option (i), (iii) and (iv)

As, K increases with increase in temperature. K increases, it shows that the reaction must be endothermic. No. of molecules increases thus, there is increase in entropy.

This is a short answer type question as classified in NCERT Exemplar

Because of hydrogen bonding HF is liquid whereas HCl is gas as there is lack of hydrogen bonding in HCl.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: option (iv) 

Since in all the given reaction, the volume is to be kept constant and an inert gas argon is added which will do not take part in reaction. So, the equilibrium will remain unaffected in all the given cases.

This is a short answer type question as classified in NCERT Exemplar

Dihydrogen reacts with dioxygen to form water. The reaction is highly exothermic.

H₂ (g) + O₂ (g) → H₂O (l)

? H = -285.9KJmol^-1

The isotope of hydrogen which has one proton and one neutron is deuterium. When it reacts with O₂ it forms Deuterium oxide (D₂O). Deuterium reacts in a similar way but the reactivity will be lesser than hydrogen because of high bond dissociation enthalpy of D₂ as compared to hydrogen.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: option (i) 

If the equation is multiplied by 2, the equilibrium constant for the new equation is the square of K it means we must do the square of 5 that is 25. Then and on reversing the reaction the value of the equilibrium constant is inversed means the value of K comes out to be 1/25= 0.04.