Class 11 Chemistry - Chapter Hydrogen NCERT Solutions | What is meant by 'demineralised'

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Compare the structures of H₂O and H₂O₂.

Write chemical reactions to show the amphoteric nature of water.

Arrange the following

(i) CaH₂, BeH₂ and TiH₂ in order of increasing electrical conductance.

(ii) LiH, NaH and CsH in order of increasing ionic character.

(iii) H-H, D-D and F-F in order of increasing bond dissociation enthalpy.

(iv) NaH, MgH₂ and H₂O in order of increasing reducing property.

Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.

What do you understand by the term “non-stoichiometric hydrides”? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.

What causes the temporary and permanent hardness of water?

How does H₂O₂ behave as a bleaching agent?

Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?

How do you account for the formation of ethane during chlorination of methane?

What are hybridisation states of each carbon atom in the following compounds ?

(i) CH₂=C=O,

(ii) CH₃CH=CH₂,

(iii) (CH₃)₂CO,

(iv) CH₂=CHCN,

(v) C₆H₆

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

What are the common physical and chemical features of alkali metals?

Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

Assign oxidation number to the underlined elements in each of the following species:

(a) NaH₂PO₄

(b) NaHSO₄

(c) H₄P₂O₇

(d) K₂MnO₄

(e) CaO₂

(f) NaBH₄

(g) H₂S₂O₇

(h) KAl(SO₄)₂.12 H₂O

What is the basic theme of organisation in the periodic table?

Explain the formation of a chemical bond.

Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?

A photon of wavelength 4 × 10^–7 m strikes on metal surface, the work function of the metal being 2.13 eV. Calculate

(i) the energy of the photon (eV),

(ii) the kinetic energy of the emission, and

(iii) the velocity of the photoelectron (1 eV= 1.6020 × 10^–19 J).

What will be the pressure of the gaseous mixture when 0.5 L of H₂ at 0.8 bar and 2.0 L of dioxygen at 0.7 bar are introduced in a 1L vessel at 27°C?

Explain the important aspects of resonance with reference to the  ion.

Rationalise the given statements and give chemical reactions :

(i) Lead(II) chloride reacts with Cl₂ to give PbCl₄.

(ii) Lead(IV) chloride is highly unstable towards heat.

(iii) Lead is known not to form an iodide, PbI₄.

H₃PO₃ can be represented by structures 1 and 2 shown below. Can these two structures be taken as the canonical forms of the resonance hybrid representing H₃PO₃? If not, give reasons for the same.

What is the maximum number of emission lines when the excited electron of an H atom in n = 6 drops to the ground state?

The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it.

For the process to occur under adiabatic conditions, the correct condition is:
(i) ΔT = 0
(ii) Δp = 0
(iii) q = 0
(iv) w = 0

Draw the Lewis structures for the following molecules and ions: H2S, SiCl4, BeF2, , HCOOH

Aluminium trifluoride is insoluble in anhydrous HF but dissolves on addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous BF₃ is bubbled through. Give reasons.