Selected MCQ

Current Question
The conjugate base of (H_2PO_4^-) is:
  • A. (H_3PO_4)
  • B. (HPO_4^{2-})
  • C. (PO_4^{3-})
  • D. (H_2PO_3^-)
Correct Answer: B
Explanation:
A conjugate base differs by loss of one proton.
Related Question 1
Which base is strong?
  • A. NH₃
  • B. NaOH
  • C. CH₃COOH
  • D. H₂O
Correct Answer: B
Explanation:
NaOH fully dissociates.
Related Question 2
Which base turns red litmus blue?
  • A. Acid
  • B. Base
  • C. Neutral
  • D. Salt
Correct Answer: B
Explanation:
Bases change litmus color.
Related Question 3
Which compound is strongest base?
  • A. NH₃
  • B. OH⁻
  • C. CH₃COO⁻
  • D. Cl⁻
Correct Answer: B
Explanation:
Hydroxide is strong base in water.
Related Question 4
Which base is found in RNA but not DNA?
  • A. Thymine
  • B. Cytosine
  • C. Uracil
  • D. Guanine
Correct Answer: C
Explanation:
RNA uses uracil instead of thymine.
Related Question 5
Aromaticity requires a cyclic, planar, conjugated system containing:
  • A. (4n) (\pi) electrons
  • B. (2n) (\sigma) electrons
  • C. (4n+2) (\pi) electrons
  • D. Any even number of (\pi) electrons
Correct Answer: C
Explanation:
Hückel’s rule specifies (4n+2) delocalized (\pi) electrons for aromatic stabilization.