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Chemistry Past Questions and Answers

Topic: The mole concept and Avogadro's number

Jamb Chemistry Questions - The mole concept and Avogadro's number

Question 1:
The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If the molar mass of X is 36 g, the number of moles of X dissolved at 343 K is
  • A 0.2 moles
  • B 0.7 moles
  • C 1.5 moles
  • D 2.0 moles
  • E 3.0 moles
View Answer & Explanation
Question 2:
An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. The empirical formula of the compound is
  • A C<sub style='font-size: smaller;'>8</sub>H<sub style='font-size: smaller;'>22</sub>O<sub style='font-size: smaller;'>3</sub>
  • B C<sub style='font-size: smaller;'>6</sub>H<sub style='font-size: smaller;'>10</sub>O<sub style='font-size: smaller;'>3</sub>
  • C C<sub style='font-size: smaller;'>12</sub>H<sub style='font-size: smaller;'>12</sub>O
  • D C<sub style='font-size: smaller;'>6</sub>H<sub style='font-size: smaller;'>12</sub>O
  • E C<sub style='font-size: smaller;'>3</sub>H<sub style='font-size: smaller;'>6</sub>O
View Answer & Explanation
Question 3:
What mass of a divalent metal M (atomic mass = 40) would react with excess hydrogen gas measured at S.T.P?
  • A 8.0 g
  • B 4.0 g
  • C 0.8 g
  • D 0.4 g
View Answer & Explanation
Question 4:
The volume occupies by 1.58g of a gas at s.t.p is 500cm3. What is the relative molecular mass of the gas?
(G.M.V at s.t.p = 22.40dm3)
  • A 28
  • B 32
  • C 44
  • D 71
View Answer & Explanation
Question 5:
2.0g of a monobasic acid was made up to 250 cm3 with distilled water. 25.00 cm3 of this solution required 20.00cm3 of 0.1 M NaOH solution for complete neutralization. The molar mass of the acid is?
  • A 200 g
  • B 160 g
  • C 100 g
  • D 50 g
View Answer & Explanation