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Chemistry Past Questions

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921
Two elements, P and Q with atomic numbers 11 and 8 respectively , combine chemically to form the compound PxQY. The respective values of x and y are?
  • A. 1 and 1
  • B. 1 and 2
  • C. 2 and 1
  • D. 3 and 1
View Answer & Discuss (5) JAMB 1997
922

Oxygen is a mixture of two isotopes 16-O and 18-O with relative abundances of 90% and 10% respectively. The relative atomic mass of oxygen is?

  • A. 16.0
  • B. 16.2
  • C. 17.0
  • D. 18.0
View Answer & Discuss (2) JAMB 1997
923

If 30cm\(^3\) of oxygen diffuses through porous plug in 7s, how long will it take 60 cm\(^3\) of chlorine to diffuse through the same plug?

  • A. 12s
  • B. 14s
  • C. 21s
  • D. 30s
View Answer & Discuss (21) JAMB 1997
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924
200 cm3 of air was passed over heated copper in a syringe several times to produce copper (II) oxide.
When cooled, the final volume of air recorded was 158cm3. Estimate the percentage of oxygen in the air?
  • A. 31%
  • B. 27%
  • C. 21%
  • D. 19%
View Answer & Discuss (2) JAMB 1997
925
On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO4. yH2O. The value of y is?

(Mg = 24, S = 32, O = 16, H = 1)
  • A. 1
  • B. 3
  • C. 5
  • D. 7
View Answer & Discuss (9) JAMB 1997
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