Science (English Medium) इयत्ता ११ - CBSE Question Bank Solutions for Chemistry

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)

Biochemical Oxygen Demand, (BOD) is a measure of organic material present in water. BOD value less than 5 ppm indicates a water sample to be ______.

Dinitrogen and dioxygen are main constituents of air but these do not react with each other to form oxides of nitrogen because ______.

Which of the following conditions shows the polluted environment.

(i) pH of rain water is 5.6.

(ii) amount of carbondioxide in the atmosphere is 0.03%.

(iii) biochemical oxygen demand 10 ppm.

(iv) eutrophication.

The consequences of global warming may be:

(i) increase in average temperature of the earth.

(ii) melting of Himalayan Glaciers.

(iii) increased biochemical oxygen demand.

(iv) eutrophication.

Dissolved oxygen in water is very important for aquatic life. What processes are responsible for the reduction of dissolved oxygen in water?

What are biodegradable and non-biodegradable pollutants?

What are the sources of dissolved oxygen in water?

What is the importance of measuring BOD of a water body?

Why does water covered with excessive algal growth become polluted?

A factory was started near a village. Suddenly villagers started feeling the presence of irritating vapours in the village and cases of headache, chest pain, cough, dryness of throat and breathing problems increased. Villagers blamed the emissions from the chimney of the factory for such problems. Explain what could have happened. Give chemical reactions for the support of your explanation.

Oxidation of sulphur dioxide into sulphur trioxide in the absence of a catalyst is a slow process but this oxidation occurs easily in the atmosphere. Explain how does this happen. Give chemical reactions for the conversion of SO₂ into SO₃.

Match the activity given in Column I with the type of pollution created by it given in Column II.

Assertion (A): If BOD level of water in a reservoir is less than 5 ppm it is highly polluted.

Reason (R): High biological oxygen demand means low activity of bacteria in water.

How can you apply green chemistry for the following:

To reduce use of synthetic detergents.

How can you apply green chemistry for the following:

To reduce the consumption of petrol and diesel.

A farmer was using pesticides on his farm. He used the produce of his farm as food for rearing fishes. He was told that fishes were not fit for human consumption because large amount of pesticides had accumulated in the tissues of fishes. Explain how did this happen?