Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

Account for the following : There is large difference between the melting and boiling points of oxygen and sulphur.

Give a simple chemical test to distinguish between the following pair of compounds :

(CH₃)₂NH and (CH₃)₃N

Write the dispersed phase and dispersion medium of butter.

Give reasons for the following : H₂Te is the strongest reducing agent amongst all the hydrides of Group 16 elements.

Write the hybridization and shape of the following complexe : [CoF₆]^3–

(Atomic number : Co = 27, Ni = 28)

Write the hybridization and shape of the following complexe : [Ni(CN)₄]^2–

^{(Atomic number : Co = 27, Ni = 28)}

What is the role of zinc metal in the extraction of silver ?

Give reasons for the following : Oxygen has less electron gain enthalpy with negative sign than sulphur.

What role does the molecular interaction play in a solution of alcohol and water?

How is the sign of Δ_mixH related to positive deviations from Raoult’s law?

Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and 35 g of octane?

Suggest the most important type of intermolecular attractive interaction in the following pair.

Acetonitrile (CH₃CN) and acetone (C₃H₆O)

Vapour pressure of pure acetone and chloroform at 328 K are 741.8 mm Hg and 632.8 mm Hg respectively. Assuming that they form ideal solution over the entire range of composition, plot P_total, `P_"chloroform"` and `P_"acetone"` as a function of `chi_"acetone"`. The experimental data observed for different compositions of mixtures is:

Plot this data also on the same graph paper. Indicate whether it has a positive  or negative deviation from the ideal solution.

If a current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons would flow through the wire?

Suggest a list of metals that are extracted electrolytically.

Consider the reaction:

\[\ce{Cr2O^{2-}_7 + 14H+ + 6e- -> 2Cr^{3+} + 7H2O}\]

What is the quantity of electricity in coulombs needed to reduce 1 mol of  \[\ce{Cr2O^{2-}_7}\]?

How much charge is required for the following reduction?

1 mol of Al³⁺ to Al.

How much charge is required for the following reduction? 

1 mol of Cu²⁺ to Cu.

How much charge is required for the following reduction? 

1 mol of \[\ce{MnO^-_4}\] to Mn²⁺.

A solution of Ni(NO₃)₂ is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?