Class 11th

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

Hydrogen economy (Hydrogen as fuel):

(i) The electricity cannot be stored in automobiles. It is not possible to store and transport nuclear energy. Hydrogen is an alternative source of energy and hence called the 'hydrogen economy". Hydrogen has some advantages as fuel.

(ii) Available in abundance in combined form as water.

(iii) On combustion produces H₂O. Hence, pollution free.

(iv) H₂O₂ fuel cells give more power.

(v) Excellent reducing agent. Therefore, it can be used as a substitute of carbon in reduction for processes in industry.

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

In sodium the last shell electron is in 3s₁ after losing that electron, it can acquire the configuration of Ne. Whereas in hydrogen, the electron is in s-orbital.

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

Because of ionization enthalpy, hydrogen resembles more with halogens, is 520 kJ mol^-1, F is 1680 kJ mol^-1and that of His 1312 kJ mol^-1. Like halogens, it forms a diatomic molecule, combining with elements to form hydrides and a large number of covalent compounds.

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

The equation can be written as-

A^p+_x  +  B^q- _y ? xA^p+ (aq) +  yB^q-

S moles of A and B dissolves to give x S moles of A^p+ and y S moles of Bq-.

K_sp = [A^p+]^x   [B^q-]^y = [x5]^x [y5]^y

= x^x y ^y 5 ^x+y

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans: option (iv) 

If the volume is kept constant and an inert gas such as argon is added which does not take part in the reaction, the equilibrium remains undisturbed.

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans:  option (iii)

Salt of weak acid and weak base can form buffer solution.

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans: K_a and K_b values are responsible for acidic and basic characters of substances. Hence option (i) is the correct answer.

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans: option (iii)

The equilibrium constant for an exothermic reaction (negative H) decreases as the temperature increases. The equilibrium constant for an endothermic reaction (positive H) increases as the temperature increases.

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans: option (ii)

In presence of H⁺ ion, equilibrium shifts in backward direction.