Science (English Medium) Class 11 - CBSE Question Bank Solutions for Chemistry

The exhibition of highest co-ordination number depends on the availability of vacant orbitals in the central atom. Which of the following elements is not likely to act as central atom in \[\ce{MF^{3-}6}\]?

Ionisation enthalpy (∆_iH₁kJ mol^–1) for the elements of Group 13 follows the order.

In the structure of diborane ______.

A compound X, of boron reacts with NH₃ on heating to give another compound Y which is called inorganic benzene. The compound X can be prepared by treating BF₃ with Lithium aluminium hydride. The compounds X and Y are represented by the formulas.

The most commonly used reducing agent is ______.

Dry ice is ______.

Cement, the important building material is a mixture of oxides of several elements. Besides calcium, iron and sulphur, oxides of elements of which of the group (s) are present in the mixture?

Which of the following statements are correct. Answer on the basis of Figure.

(i) The two birdged hydrogen atoms and the two boron atoms lie in one plane;

(ii) Out of six B – H bonds two bonds can be described in terms of 3 centre 2-electron bonds.

(iii) Out of six B – H bonds four B – H bonds can be described in terms of 3 centre 2 electron bonds;

(iv) The four-terminal B – H bonds are two centre-two electron regular bonds.

Explain why the following compounds behave as Lewis acids?

BCl₃

Explain why the following compounds behave as Lewis acids?

AlCl₃

When BCl₃ is treated with water, it hydrolyses and forms [B[OH]₄]^– only whereas AlCl₃ in acidified aqueous solution forms [Al(H₂O)₆]³⁺ ion. Explain what is the hybridisation of boron and aluminium in these species?

Aluminium dissolves in mineral acids and aqueous alkalies and thus shows amphoteric character. A piece of aluminium foil is treated with dilute hydrochloric acid or dilute sodium hydroxide solution in a test tube and on bringing a burning matchstick near the mouth of the test tube, a pop sound indicates the evolution of hydrogen gas. The same activity when performed with concentrated nitric acid, reaction doesn’t proceed. Explain the reason.

Explain the following:

Boron does not exist as B³⁺ ion.

Explain the following:

PbX₂ is more stable than PbX₄.

Explain the following:

Pb⁴⁺ acts as an oxidising agent but Sn²⁺ acts as a reducing agent.

Explain the following:

Electron gain enthalpy of chlorine is more negative as compared to fluorine.

Explain the following:

Tl (NO₃)₃ acts as an oxidising agent.

Identify the compounds A, X and Z in the following reactions:

\[\ce{A + 2HCl + 5H2O -> 2NaCl + X}\]

Identify the compounds A, X and Z in the following reactions:

\[\ce{X ->[Δ][370 K] HBO2 ->[Δ][> 370 K] Z}\]

Complete the following chemical equations:

\[\ce{Z + 3 LiAlH4 -> X + 3LiF + 3AlF_3}\]

\[\ce{X + 6H2 -> Y + 6H2}\]

\[\ce{3X + 3O2 ->[Δ] B2O3 + 3H2O}\]