Some Basic Principles and Techniques

This is a Multiple Choice Questions as classified in NCERT Exemplar

37. Option

(iii) CH₃ - CH₂ - C ≡ *CH is correct since electronegativity of carbon depends on its hybridized state and percentage of s-character. Electronegativity ∝ percentage of  s-character.

So, the order of percentage 's' character is given as-

 sp³ (25%) < sp² (33%) < sp (50%)

In option (iii) Carbon linked through triple bond and is sp hybridized hence it is highly electronegative.

This is a Multiple Choice Questions as classified in NCERT Exemplar

36. Option (ii) 1-Chloro-4-methyl-2-nitrobenzene is correct since the substituent of the base compound is given number 1 and then the direction of numbering is chosen in such a manner that the next substituent gets the lowest number. The substituents that appear in the IUPAC name are in alphabetical order.  Hence in this case numbering can be shown as-

This is a Multiple Choice Questions as classified in NCERT Exemplar

35. Option (iv) 4-oxopentanoic acid is correct  since more than one functional group is present in the chain so, out of the two functional groups one will be given more priority as a result numbering is done from that side and mentioned as a sec. suffix, while the other one is written as prefix and mentioned as oxo along with the locant.

This is a Multiple Choice Questions as classified in NCERT Exemplar

34. Option (i) 3-Ethyl-4, 4-dimethylheptane is correct since in IUPAC naming the different alkyl groups present are written in alphabetical order. Di, tri, tetra are not included in the alphabetical order. So, “e” of the ethyl group comes before the “m” of the dimethyl group. The number 3 is given to the ethyl group and is written first. 

33. Resonating structure of A

In this case structure II is less stable than I because in structure II separation of positive and negative charges is there. Therefore, contribution of structure (II) is less than that of (I), these hybrids of compound (A) i.e., CH₃COOH.

Resonating structure of B

While structure (III) and (IV) are of equal energy and also contribute equally towards, resonance hybrid of compound (B). Therefore, CH3COO- is more stable.

32. Mixture of alcohol and hydrocarbon can be separated by simple distillation because both the components have large differences in their boiling points. When temperature is raised to the low boiling liquid i.e., hydrocarbon, the vapours consist only of hydrocarbons without any contamination of alcohol.

31. The structure-I of propenal is found to be more stable because structure having more covalent bonds in a resonating structure is found to have more stability, in structure II, the terminal carbon has only six electrons which makes it less stable. 

30. SO₃ acts as an electrophile as in this, three highly electronegative oxygen atoms are attached to the sulphur atom which makes it electron deficient. It can be shown by resonance that it gets positive charge and acts as an electrophile.

29. SO₃ acts as an electrophile as in this, three highly electronegative oxygen atoms are attached to the sulphur atom which makes it electron deficient. It can be shown by resonance that it gets positive charge and acts as an electrophile.