# Important 5 Marks Questions for CBSE 11 Chemistry Exam

## Important 5 Marks Questions

Ques 1:

Explain the following reactions:

1. Silicon is heated with methyl chloride at high temperature in the presence of copper powder
2. CO is heated with ZnO
3. Reaction of boron trifluoride with LiAlH4 in diethyl ether
4. Reaction of boron trifluoride with sodium hydride at 450 K
5. Reaction of diborane and water

Ques 2:

Explain giving reasons for the following:

1. Boron does not form B3+ ions.
2. Molten aluminium bromide is a poor conductor of electricity.
3. BCl3 is more stable than TlCl3.
4. B-Cl bond has a dipole moment but BCl3 has zero dipole moment.
5. Al is used to make transmission cables.

Ques 3:

For the reaction NH4Cl s-> NH3 g + HCl g        at 25°C, enthalpy change ΔH=+ 177 kJ mol-1 and entropy change ΔS=+285JK-1 mol-1 . Calculate free energy change o ΔG at 25 C and predict whether the reaction is spontaneous or not.

Ques 4:

(a) Compound ‘A’ with the molecular formula C5 H8 reacts with hydrogen in [5] the presence of Lindlar’s catalyst to form a compound B with the molecular formula C5 H10 . A on reacting with sodium in liquid ammonia forms a compound ‘C’ with the same molecular formula as that of B. Identify ‘A’, ‘B’ and ‘C’. Give the chemical reactions involved.

(b) Write the chemical reaction involved in Kolbe’s electrolytic process. What are the products formed at cathode and anode?

Ques 5:

Define compressibility factor? Explain how the function PV/RT (Z) can be used to show gases behave non-ideally at different pressure

Ques 6:

Explain the classification elements into ‘s,p,d & f’ block elements. Explain with suitable examples. Write their general electronic configuration.

Ques 7:

1. a) What is meant molarity of a solution? What are its units?
2. b) Calculate the molarity of H2SO4 in the solution prepared by dissolving 49 grams of it in enough water to form 250 mL of the solution.
3. c) Find the weight of sodium carbonate dissolved in 250mL of 0.1M Na2CO3 solution

Ques 8:

(a) Explain the terms Inductive and Electromeric effects.

(b) write the total structural isomers possible for C4H10O

Ques 9:

Define ionic bond .Explain the factors that influence the formation of an Ionic bond with suitable examples.

Ques 10:

What are quantum numbers? What permitted values can these have? Explain their significance.

Ques 11:

1. a) Convert :
2. i) Benzene to p-nitrobromobenzene
3. ii) Ethyl chloride to ethene.
4. b) Give mechanism of addition of HBr to propene.
5. c) Write a note on Friedel-Crafts alkylation

Ques 12:

Balance the following equation in acidic medium by half reaction method.

${Cr_2O_7}^{2-} + C_2H_4O \rightarrow C_2H_4O_2 + Cr^{3+}$

Ques 13:

(a) Give one method for industrial preparation and one for laboratory preparation of CO and CO2 each.

(b) Select the member(s) of group 14 that

1. i) forms the most acidic dioxide
2. ii) used as semiconductors.

(c) Explain structure of Diborane

Ques 14:

Convert the following:

1. a) Benzene to Benzoic acid
2. b) Bromoethane to Butan-1-ol
3. c) Ethene to Propene
4. d) Ethyne to Methane
5. e) Propene to Propan-2-ol

Ques 15:

Write the balanced ionic equation for the reaction of permanganate ion with bromide ion in basic medium to give manganese dioxide and bromate ion.