Ncert Solutions Chemistry Class 11th
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14.32 The main constituents of air are
(a) N2 and O2 (b) SO2 and CO2 (c) CO and CO2 (d) none of the above
14.32 The main constituents of air are
(a) N2 and O2 (b) SO2 and CO2 (c) CO and CO2 (d) none of the above
MCQs
14.31 . Which of the following statements is incorrect?
(a) The atmosphere that surrounds the earth isnot of the same thickness at all heights.
(b) The lowest regionof atmosphere in which the human beingsalong with other organisms live is calledtroposphere.
(c) Below the troposphere,between 10 and 50 km above sea level lies stratosphere.
(d) Troposphere is a turbulent,
dusty zone containing air, much water vapour
and clouds.
MCQs
14.31 . Which of the following statements is incorrect?
(a) The atmosphere that surrounds the earth isnot of the same thickness at all heights.
(b) The lowest regionof atmosphere in which the human beingsalong with other organisms live is calledtroposphere.
(c) Below the troposphere,between 10 and 50 km above sea level lies stratosphere.
(d) Troposphere is a turbulent,
dusty zone containing air, much water vapour
and clouds.
(c) Stratosphere is above the troposphere.
Upvote 
14.28 Assertion: Tetra chlroroethene was earlier used as solvent for dry cleaning, which now a days are discontinued.
Reason: Chlorine gas was used earlier for bleaching
14.28 Assertion: Tetra chlroroethene was earlier used as solvent for dry cleaning, which now a days are discontinued.
Reason: Chlorine gas was used earlier for bleaching
(b) The compound contaminates the ground water and is also a suspected carcinogen.
Upvote 14.27 Assertion: CO is a colourless and odourless gas, highly poisonous to living beings.
Reason: It is produced as a result of incomplete combustion of carbon and is mainly released into the air by automobile exhaust.
14.27 Assertion: CO is a colourless and odourless gas, highly poisonous to living beings.
Reason: It is produced as a result of incomplete combustion of carbon and is mainly released into the air by automobile exhaust.
(b) CO is highly poisonous to living beings because of its ability to block the delivery of oxygen to the organs and tissues.
Upvote 13.25. Why is Wurtz reaction not preferred for the preparation of alkanes containing odd number of carbon atoms? Illustrate your answer by taking one example.
13.25. Why is Wurtz reaction not preferred for the preparation of alkanes containing odd number of carbon atoms? Illustrate your answer by taking one example.
Alkyl halides on treatment with sodium metal in dry ethereal (free from moisture) solution give higher alkanes. This reaction is known as Wurtz reaction and is used for the preparation of higher alkanes containing even number of carbon atoms.
For preparation of alkanes containing odd number of carbon
Upvote 3.46. Choose the incorrect statement
(a) In a triad, the atomic mass of the middle element is the mean of the atomic masses of the first and third elements.
(b) Electronegativity refers to the tendency of atom so share electrons with another atom.
(c) Number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled.
(d) According to Mendeleev, periodic properties of elements are a function of their atomic masses.
3.46. Choose the incorrect statement
(a) In a triad, the atomic mass of the middle element is the mean of the atomic masses of the first and third elements.
(b) Electronegativity refers to the tendency of atom so share electrons with another atom.
(c) Number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled.
(d) According to Mendeleev, periodic properties of elements are a function of their atomic masses.
3.46. (b) Electronegativity refers to the tendency of an atom to share electrons with another atom.
Upvote 13.24. Suggest the name of a Lewis acid other than anhydrous aluminium chloride which can be used during ethylation of benzene.
13.24. Suggest the name of a Lewis acid other than anhydrous aluminium chloride which can be used during ethylation of benzene.
Anhydrous Ferric Chloride (FeCl3) is another Lewis acid which can be used during ethylation of benzene.
Upvote 13.23. Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and why?
13.23. Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and why?
CH3 group is electron-donating while -NO2 group is electron-withdrawing. Therefore, maximum electron density will be in toluene, followed by benzene and least in m-dinitrobenzene. Therefore, the ease of nitration decreases in the order: toluene > benzene > m-dinitrobenzene.
Upvote 13.22. Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+.
(a) Chlorobenzene, 2, 4-dinitrochlorobenzene, p-nitrochlorobenzene
(b) Toluene,p—H3C—C6H4—NO2, p—O2N—C6H4—NO2.
13.22. Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+.
(a) Chlorobenzene, 2, 4-dinitrochlorobenzene, p-nitrochlorobenzene
(b) Toluene,p—H3C—C6H4—NO2, p—O2N—C6H4—NO2.
(a) The typical reactions of benzene are electrophilic substitution reactions. Higher the electron-density in the benzene ring, more reactive is the compound towards thesereactions. Since NO2 is a more powerful electron-withdrawing group than Cl, therefore, more the number of nitro groups, less rea
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