Chemistry MCQ

admin January 15, 2024

1. Which of the following is a nonpolar molecule?

(a) HCl

(b) CH₃Cl

(d) NH₃

Answer. (c)

2. Which is defined as a species that accepts a proton?

(a) Lewis acid

(b) Lewis base

(d) Bronsted-Lowry base

Answer. (d)

3. Which statement is correct about acid-base chemistry?

(a) the larger the K_a, the stronger the acid

(b) a small pK_a correspond to a large K_a

(d) all of the above

Answer. (d)

4. Which of the following statements is correct?

(a) The stronger the acid, the weaker its conjugate base.

(b) The stronger the acid, the stronger its conjugate base.

(d) The stronger the acid, the weaker its conjugate acid.

Answer. (a)

5. What is the conjugate acid of CH₃NH₂?

(a) CH₃NH₃⁺

(b) CH₃NH^–

(d) NH₂^–

Answer. (a)

6. What is the conjugate base of CH₃NH₂?

(a) CH₃NH₃⁺

(b) CH₃NH^–

(d) NH₂^–

Answer. (b)

7. The stronger the acid —————.

(a) the less stable its conjugate base

(b) the larger the pK_a

(d) the larger the pH

Answer. (c)

8. Which of the following is the strongest acid?

(b) H₂O

(d) CH₃OH

Answer. (a)

9. Which of the following are Lewis bases?

(a) NF₃

(b) BF₃

(d) (a) and (c)

Answer. (d)

10. Which of the following is not a characteristic of organic compounds?

(a) They usually have low melting points.

(b) They usually are only slightly soluble or insoluble in water.

(d) Bonds which bind the atoms together are nearly always ionic.

Answer. (d)

11. The element least likely to be found in an organic compound is

(a) oxygen

(b) sulfur

(d) silicon

Answer. (d)

12. One of the major sources of organic compounds is

(a) Natural gas

(b) Fermentation

(d) Atmosphere

Answer. (a)

13. Catenation is a property of the carbon atom which describes its ability to

(a) bond with other carbon atoms

(b) form double and triple bonds

(d) form bonds in its ground state

Answer. (a)

14. In stable organic compounds, carbon will always form

(a) 2 bonds

(b) 4 bonds

(d) 5 bonds

Answer. (b)

15. Carbon-carbon double bonds consist of :

(a) one σ bond, one π bond

(b) two σ bonds, one π bond

(d) two σ bonds, two π bonds

Answer. (a)

16. Acetylene has a total of:

(a) one σ bond, two π bonds

(b) two σ bonds, four π bonds

(d) one σ bond, four π bonds

Answer. (c)

17. In propene there are

(a) eight σ bonds and one π bond

(b) seven σ bonds and two π bonds

(d) nine σ bonds

Answer. (a)

18. In propyne there are

(a) six σ bonds and two π bonds

(b) seven σ bonds and one π bond

(d) eight σ bonds

Answer. (a)

19. 1-Buten-3-yne has

(a) six σ and four π bonds

(b) seven σ and three π bonds

(d) nine σ and one π bond

Answer. (b)

20. Compound in which carbons use only sp³ hybrid orbitals for bond formation is

(a) CH₃CH₂CH₃

(b) CH₃CCH

Answer. (a)

21. Compound in which carbon uses sp3 hybrid orbitals for bond formation is

(a)

(b)

(c)

(d) (CH₃)₃COH

Answer. (d)

22. When the carbon atom is sp² hybridized in a compound, it is bonded to

(a) 2 other atoms

(b) 4 other atoms

(d) 5 other atoms

Answer. (c)

23. Compound in which carbons use only sp² hybrid orbitals for bond formation is

(a)

(b)

(d) CH₃CH=C=CH₂

Answer. (c)

24. Which of the following is a planar molecule?

(a) Formaldehyde

(b) Acetone

(d) Acetic acid

Answer. (a)

25. What is bond angle between the hybrid orbitals in methane?

(a) 180⁰

(b) 120⁰

(d) 115.5⁰

Answer. (c)

26. The H—C—C bond angle in ethane is

(a) 60⁰

(b) 109.5⁰

(d) 118⁰28′

Answer. (b)

27. The H—C—H bond angle in ethylene is

(a) 60⁰

(b) 120⁰

(d) 180⁰

Answer. (b)

28. What is the bond length of a carbon-carbon double bond?

(a) 1.20 Å

(b) 1.34 Å

(d) 1.68 Å

Answer. (b)

29. The carbon-carbon bond lengths in rank of increasing bond length is :

(a) triple, double, single

(b) single, double, triple

(d) triple, single, double

Answer. (a)

30. Which of the following is the correct order of bond lengths •

(a) C-C < C=C < CC

(b) C-C > CC > C=C

(d) CC < C-C > C=C

Answer. (a)

31. Which of the following hydrocarbons has the shortest C—C bond length?

(a) CH₂=CH₂

(b) CH₃CH₃

(d)

Answer. (c)

32. The carbon-carbon bond length is maximum in

(a) CH₂=CH₂

(b) CH3CH3

(d)

Answer. (b)

33. What is the hybridization of the carbon atoms numbered 1 and 2 respectively in the following structure?

(a) sp³, sp²

(b) sp², sp²

(d) sp², sp

Answer. (d)

34. How many atoms are attached to an atom having a sp hybridization?

(a) 0

(b) 1

(d) 3

Answer. (c)

35. Which statement is true?

(a) Resonance hybrids are inherently unstable.

(b) Resonance hybrids are more stable than any individual resonance form.

(d) Resonance hybrids are averages of all resonance forms resembling the more stable forms.

Answer. (d)

36. Resonance structures of a molecule have

(a) same arrangement of atoms

(b) different arrangement of atoms

(d) different number of paired electrons

Answer. (a) and (c)

37. Which of the following compounds have planar molecules?

(a) ethyl alcohol

(b) formaldehyde

(d) 1,3-butadiene

Answer. (b) and (d)

38. Which of the following compounds will show dipole moment?

(a) cis-1,2-dichloroethylene

(b) 0-dichlorobenzene

(d) p-dichlorobenzene

Answer. (a) and (b)

39. Which molecule has a nonzero dipole moment?

(a) Cl₂

(b) CO₂

(d) CHCl₃

Answer. (d)

40. Which of the following compounds have lowest dipole moment?

(a) carbon tetrachloride

(b) chloromethane

(d) chloroform

Answer. (a)

41. Homolytic fission of C—C bond leads to the formation of :

(a) Free radicals

(b) Carbonium ions

(d) None of these

Answer. (a)

42. Homolytic fission of covalent bond between carbon atoms will produce :

(a) Two carbonium ions

(b) Two molecules

(d) Carbonium ion and carbanion

Answer. (c)

4. The order of stability of carbonium ions is

(a) tertiary > secondary > primary

(b) secondary > tertiary > primary

(d) primary > tertiary > secondary

Answer. (a)

44. The order of stability of carbanions is

(a) primary > secondary > tertiary

(b) secondary > tertiary > primary

(d) tertiary > primary > secondary

Answer. (a)

45. Which molecule has the greatest dipole moment

(a) CH₃Cl

(b) CH₃Br

(d) CH₃l

Answer. (c)

46. Which of the following compounds have highest dipole moment?

(a) dichloromethane

(b) chloroform

(d) carbon tetrachloride

Answer. (a)

47. Which of the following carbonium ions will be most stable?

(a) $\displaystyle \overset{+}{\mathop{C}}\,{{H}_{3}}$

(b) $\displaystyle C{{H}_{3}}\overset{+}{\mathop{C}}\,{{H}_{2}}$

(d) $\displaystyle C{{H}_{2}}=CH\overset{+}{\mathop{C}}\,{{H}_{2}}$

Answer. (d)

49. The least stable carbanion is :

(a) $\displaystyle {{C}_{6}}{{H}_{5}}\overset{-}{\mathop{C}}\,{{H}_{2}}$

(b) $\displaystyle {{\left( {C{{H}_{3}}} \right)}_{3}}\overset{-}{\mathop{C}}\,$

(d) $\displaystyle \overset{-}{\mathop{C}}\,{{H}_{3}}$

Answer. (b)

49. Which alkyl free radical is the most stable?

(a) methyl

(b) primary

(d) tertiary

Answer. (d)

50. Which of the following is an electrophile?

(a) $\displaystyle C{{H}_{3}}\overset{-}{\mathop{O}}\,$

(b) $\displaystyle C{{H}_{3}}\overset{+}{\mathop{C}}\,{{H}_{2}}$

(d) $\displaystyle C{{H}_{3}}\overset{-}{\mathop{C}}\,{{H}_{2}}$

Answer. (b)

Gyanpoints

Chemistry MCQ

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