Science (English Medium) कक्षा ११ - CBSE Question Bank Solutions

E^Θ values of some redox couples are given below. On the basis of these values.

E^Θ values: \[\ce{Br2 /Br- = + 1.90; Ag+ / Ag(s) = + 0.80}\];

\[\ce{Cu^{2+} / Cu(s) = + 0.34; I2(s) / I- = 0.54}\]

Consider the reactions

(A) \[\ce{H2O2 + 2HI -> I2 + 2H2O}\]

(B) \[\ce{HOCl + H2O2 -> H3O+ + Cl- + O2}\]

Which of the following statements is correct about \[\ce{H2O2}\] with reference to these reactions? Hydrogen perioxide is ______.

Elements of which of the following group(s) of periodic table do not form hydrides.

When the first element of the periodic table is treated with dioxygen, it gives a compound whose solid-state floats on its liquid state. This compound has an ability to act as an acid as well as a base. What products will be formed when this compound undergoes authorisation?

Give reasons why hydrogen resembles alkali metals?

The alkali metals are low melting. Which of the following alkali metal is expected to melt if the room temperature rises to 30°C?

Alkali metals react with water vigorously to form hydroxides and dihydrogen. Which of the following alkali metals reacts with water least vigorously?

The order of decreasing ionisation enthalpy in alkali metals is ______.

Metals form basic hydroxides. Which of the following metal hydroxide is the least basic?

The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to ______.

In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH₄Cl with Ca(OH)₂. The by-product obtained in this process is ______.

By adding gypsum to cement

Which of the following elements does not form hydride by direct heating with dihydrogen?

Metallic elements are described by their standard electrode potential, fusion enthalpy, atomic size, etc. The alkali metals are characterised by which of the following properties?

(i) High boiling point.

(ii) High negative standard electrode potential.

(iii) High density.

(iv) Large atomic size.

Which of the following compounds are readily soluble in water?

(i) BeSO₄

(ii) MgSO₄

(iii) BaSO₄

(iv) SrSO₄ 

Choose the correct statements from the following.

(i) Beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal.

(ii) Beryllium sulphate is readily soluble in water as the greater hydration enthalpy of Be²⁺ overcomes the lattice enthalpy factor.

(iii) Beryllium exhibits coordination number more than four.

(iv) Beryllium oxide is purely acidic in nature.

When heated in air, the alkali metals form various oxides. Mention the oxides formed by Li, Na and K.

Write Lewis strucure of \[\ce{O^{-}2}\] ion and find out oxidation state of each oxygen atom? What is the average oxidation state of oxygen in this ion?

When a metal of group 1 was dissolved in liquid ammonia, the following observations were obtained:

(i) Blue solution was obtained initially.

(ii) On concentrating the solution, blue colour changed to bronze colour.

How do you account for the blue colour of the solution? Give the name of the product formed on keeping the solution for some time.

The stability of peroxide and superoxide of alkali metals increase as we go down the group. Explain giving reason.