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

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.

Ions of an element of group 1 participate in the transmission of nerve signals and transport of sugars and aminoacids into cells. This element imparts yellow colour to the flame in flame test and forms an oxide and a peroxide with oxygen. Identify the element and write chemical reaction to show the formation of its peroxide. Why does the element impart colour to the flame?

The element which exists in liquid state for a wide range of temperature and can be used for measuring high temperature is ______.

Electronegativity of carbon atoms depends upon their state of hybridisation. In which of the following compounds, the carbon marked with asterisk is most electronegative?

Explain, how is the electronegativity of carbon atoms related to their state of hybridisation in an organic compound?

Assertion (A): All the carbon atoms in H₂C = C = CH₂ are sp² hybridised

Reason (R): In this molecule all the carbon atoms are attached to each other by double bonds.

The ring systems having following characteristics are aromatic.

(i) Planar ring containing conjugated π bonds.

(ii) Complete delocalisation of the π−electrons in ring system i.e. each atom in the ring has unhybridised p-orbital, and

(iii) Presence of (4n + 2) π−electrons in the ring where n is an integer (n = 0, 1, 2,...........) [Huckel rule].

Using this information classify the following compounds as aromatic/non-aromatic.

(A)	(B)	(C)	(D)
(E)	(F)	(G)

Which of the following compounds are aromatic according to Huckel’s rule?

(A)	(B)	(C)

(D)	(E)	(F)

Indicate the σ and π bonds in the following molecules:

HCONHCH₃

Indicate the σ and π bonds in the following molecules:

HCONHCH₃

Indicate the σ and π bonds in the following molecule:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecules:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecules:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecule:

\[\ce{HCONHCH3}\]