21. The structure of triphenylmethyl cation is given below. This is very stable and some of its salts can be stored for months. Explain the cause of high stability of this cation
21. Triphenylmethyl cation is found to be very much stable as this positive charge on methyl carbon is delocalized in three phenyl rings. In each phenyl ring, positive charge is developed on 2 ortho position and para position, i.e., three resonating structures. Total resonating structures given by triphenylmethyl cation are nine. Hence, it is very stable. These structures can be shown as.
<p><strong>21. </strong>Triphenylmethyl cation is found to be very much stable as this positive charge on methyl carbon is delocalized in three phenyl rings. In each phenyl ring, positive charge is developed on 2 ortho position and para position, i.e., three resonating structures. Total resonating structures given by triphenylmethyl cation are nine. Hence, it is very stable. These structures can be shown as.</p><div><div><picture><source srcset="https://images.shiksha.com/mediadata/images/articles/1743659244phpd1FNNo_480x360.jpeg" media=" (max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/articles/1743659244phpd1FNNo.jpeg" alt="" width="455" height="197"></picture></div></div>
This is a Assertion Type Questions as classified in NCERT Exemplar
65. Option (i)
i.e., Both A and R are correct, and R is the correct explanation of A is the answer since in paper chromatography, a special quality of paper known as chromatography paper is used. Chromatography paper contains water molecules trapped in it which acts as the stationary phase. A strip of chromatography paper spotted at the base with the solution of the mixture is suspended in a suitable solvent or a mixture of solvents which acts as the mobile phase. The solvent rises up the paper by capillary action and flows over the spot. The paper selectively
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This is a Assertion Type Questions as classified in NCERT Exemplar
65. Option (i)
i.e., Both A and R are correct, and R is the correct explanation of A is the answer since in paper chromatography, a special quality of paper known as chromatography paper is used. Chromatography paper contains water molecules trapped in it which acts as the stationary phase. A strip of chromatography paper spotted at the base with the solution of the mixture is suspended in a suitable solvent or a mixture of solvents which acts as the mobile phase. The solvent rises up the paper by capillary action and flows over the spot. The paper selectively retains different components according to their differing partition in the two phases. During this process the paper strip so developed is known as a chromatogram and the spots of the separated coloured compounds are visible at different heights from the position of the initial spot on the chromatogram.
This is a Assertion Type Questions as classified in NCERT Exemplar
64. Option (iii) i.e., Both A and R are not correct is the answer since sulphur is estimated by Carius method in the form of white precipitate of BaSO4 on heating with fuming and BaCl2. If light yellow solid is obtained means impurities are present. It is filtered, washed and then dried to get pure BaSO4 .
This is a Assertion Type Questions as classified in NCERT Exemplar
63. Option (iv) i.e., A is not correct, but R is correct is the answer since hybridization of C can be found out by counting σ bonds and π bonds present on C atom. This can be shown as-
If C has 3σ bonds then it is sp2 hybridized. If C has 2σ bonds then it is sp hybridized.
This is a Assertion Type Questions as classified in NCERT Exemplar
62. Option (i) i.e.,
Both A and R are correct, and R is the correct explanation of A is the answer as when two or more compounds differ in the position of substituent atom or functional group on the carbon skeleton, they are known as position isomers and this phenomenon is termed as position isomerism. Pent-2-ene and pent-l-ene are position isomers because they differ in the position of the double bond.
This is a Assertion Type Questions as classified in NCERT Exemplar
61. Option (iv)
i.e., A is not correct, but R is correct is the answer. This is because canonical structures always have more energy than the resonance hybrid. Resonance hybrids are always found to be more stable than any of the canonical structures since the delocalization of electrons lowers the orbitals energy and gives stability.
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