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Chemistry Past Questions

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11

The electronic configuration of an elements is 1s22s22p63s23p3. How many unpaired electrons are there in the element?

  • A. 5
  • B. 4
  • C. 3
  • D. 2
View Answer & Discuss (13) JAMB 1991
12

Allotropes are elements having?

  • A. different physical but the same chemical properties
  • B. different chemical but the same physical properties
  • C. the same chemical and physical properties
  • D. different atomic structure
  • E. the same position in the periodic table
View Answer & Discuss (29) JAMB 1981
13

An element X has two isotopes, \(^{20} _{10}X\) and \(^{22} _{10}X\),
present in the ratio 1:3. The relative atomic mass of X would be?

  • A. 20.5
  • B. 21.0
  • C. 21.5
  • D. 22.0
  • E. 22.5
View Answer & Discuss (41) JAMB 1982
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14

2.25g of a sample of an oxide of copper on reduction gave 2.0g of copper. 2.50g of another oxide of copper on reduction also gave 2.0g of copper. These results are in accordance with the law of?

  • A. constant composition
  • B. conservation of matter
  • C. multiple proportions
  • D. definite proportions
View Answer & Discuss (18) JAMB 1988
15

What is the number of oxygen atoms in 32g of the gas? (O = 16, L = 6.0 X 10\(^{23}\) mol\(^{-1}\))

  • A. 3.2 X 10 23
  • B. 6.0 X 1023
  • C. 1.2 X 1024
  • D. 1.6 X 1024
  • E. 2.0 X 1024
View Answer & Discuss (17) WAEC 1992
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