Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

List the important sources of sulphur.

Write the order of thermal stability of the hydrides of Group 16 elements.

Why is H₂O a liquid and H₂S a gas?

Which of the following does not react with oxygen directly?

Zn, Ti, Pt, Fe

Why does NH₃ form hydrogen bond but PH₃ does not?

The HNH angle value is higher than HPH, HAsH and HSbH angles. Why? [Hint: Can be explained on the basis of sp³ hybridisation in NH₃ and only s−p bonding between hydrogen and other elements of the group].

Justify the placement of O, S, Se, Te and Po in the same group of the periodic table in terms of electronic configuration, oxidation state and hydride formation.

Knowing the electron gain enthalpy values for \[\ce{O -> O-}\] and \[\ce{O -> O^{2-}}\] as −141 and 702 kJ mol⁻¹ respectively, how can you account for the formation of a large number of oxides having O²⁻ species and not O⁻?

(Hint: Consider lattice energy factor in the formation of compounds).

Why are halogens strong oxidising agents?

Explain why inspite of nearly the same electronegativity, oxygen forms hydrogen bonding while chlorine does not.

Give reasons:

The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.

Arrange the following in the order of property indicated for the given set:

F₂, Cl₂, Br₂, I₂ - increasing bond dissociation enthalpy.

State second law of electrolysis

Complete the given chemical equations 

`F_2 + 2Cl^(-)`

What happens when HCl is added to MnO₂? Write the equations involved

Give reasons Thermal stability decreases from H₂O to H₂Te.

Calculate the mass of Ag deposited at cathode when a current of 2 amperes was passed through a solution of AgNO₃ for 15 minutes.

(Given : Molar mass of Ag = 108 g mol⁻¹ lF = 96500 C mol⁻¹)

Draw the structures of `H_3PO_2`

Write the name of the cell which is generally used in transistors. Write the reactions taking place at the anode and the cathode of this cell.

Write the hybridisation and number of unpaired electrons in the complex `[CoF_6]^(3-)`. (Atomic No. of Co = 27)