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Unit 14: Some Basic Principles of Organic Chemistry — Online MCQ Test

CHEMISTRY · NEET (All) · NEET
Practice Unit 14: Some Basic Principles of Organic Chemistry with a free chapter-wise online MCQ test. This chapter covers: Tetravalency of carbon: Shapes of simple molecules - hybridization (s and p): Classification of organic compounds based on functional groups: and those containing halogens oxygen n.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Unit 14: Some Basic Principles of Organic Chemistry — Important Questions & Answers

A tertiary butyl carbocation is more stable than a secondary butyl carbocation because of which of the following?
  • A. +R effect of -CH3 groups
  • B. -R effect of -CH3 groups
  • C. Hyperconjugation
  • D. -I effect of -CH3 groups
Answer: C. Hyperconjugation
Carbocation stability increases with more alkyl groups due to inductive effect and hyperconjugation. Hyperconjugation with adjacent C-H bonds provides additional stability.
The correct order of decreasing acidity of the following aliphatic acids is:
  • A. (CH₃)₃CCOOH > (CH₃)₂CHCOOH > CH₃COOH > HCOOH
  • B. CH₃COOH > (CH₃)₂CHCOOH > (CH₃)₃CCOOH > HCOOH
  • C. HCOOH > CH₃COOH > (CH₃)₂CHCOOH > (CH₃)₃CCOOH
  • D. HCOOH > (CH₃)₃CCOOH > (CH₃)₂CHCOOH > CH₃COOH
Answer: C. HCOOH > CH₃COOH > (CH₃)₂CHCOOH > (CH₃)₃CCOOH
Acidity decreases as the +I effect of alkyl groups increases, which destabilizes the conjugate base. HCOOH > primary > secondary > tertiary.
Total number of possible isomers (both structural as well as stereoisomers) of cyclic ethers of molecular formula C4H8O is:
  • A. 6
  • B. 8
  • C. 10
  • D. 11
Answer: C. 10
Isomers include oxetane, 2-methyloxetane, 3-methyloxetane, tetrahydrofuran, and oxirane derivatives including stereoisomers (cis/trans). Total count is 10.
Total number of possible isomers (both structural as well as stereoisomers) of cyclic ethers of molecular formula C4H8O is:
  • A. 6
  • B. 8
  • C. 10
  • D. 11
Answer: C. 10
Cyclic ethers with formula C4H8O include oxetane (1 isomer), 2-methyloxetane (2 isomers), 3-methyloxetane (1 isomer), tetrahydrofuran (1 isomer), and oxirane derivatives (e.g., ethyl oxirane, 2,2-dimethyl oxirane, 2,3-dimethyl oxirane). Accounting for stereoisomers, there are 10 total.
With respect to the conformers of ethane, which of the following statements is true?
  • A. Both bond angles and bond length remains same
  • B. Bond angle remains same but bond length changes
  • C. Bond angle changes but bond length remains same
  • D. Both bond angle and bond length change
Answer: A. Both bond angles and bond length remains same
Conformations of ethane are generated by rotation around the C-C single bond. This rotation does not affect the bond lengths or bond angles between atoms.