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Sunday, 21 June 2026
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Chemistry Past Questions and Answers

Jamb Chemistry Questions

Question 226:
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
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Question 227:
A polymerization reaction is one in which?
  • A Small molecules form giant molecules
  • B Atoms form molecules
  • C Giant molecules form small molecules
  • D Molecules form volatile compounds
  • E A molecule rearranges itself
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Question 228:
Which of the following is the electronic configuration of sodium?
(Atomic number of Na = 11)
  • A 1s<sup style='font-size: smaller;'>2</sup> 2s<sup style='font-size: smaller;'>2</sup>2p<sup style='font-size: smaller;'>6</sup> 3s<sup style='font-size: smaller;'>2</sup>
  • B 1s<sup style='font-size: smaller;'>2</sup> 2s<sup style='font-size: smaller;'>2</sup>2p<sup style='font-size: smaller;'>6</sup> 3s<sup style='font-size: smaller;'>2</sup> 3p1s<sup style='font-size: smaller;'>2</sup> 2s<sup style='font-size: smaller;'>2</sup>2p<sup style='font-size: smaller;'>6</sup> 3s<sup style='font-size: smaller;'>1</sup>
  • C 1s<sup style='font-size: smaller;'>2</sup> 2s<sup style='font-size: smaller;'>2</sup>2p<sup style='font-size: smaller;'>6</sup> 3s<sup style='font-size: smaller;'>1</sup>
  • D 1s<sup style='font-size: smaller;'>2</sup> 2s<sup style='font-size: smaller;'>2</sup>2p<sup style='font-size: smaller;'>6</sup> 3s<sup style='font-size: smaller;'>°</sup>
  • E 1s<sup style='font-size: smaller;'>2</sup> 2s<sup style='font-size: smaller;'>2</sup>2p<sup style='font-size: smaller;'>6</sup> 4s<sup style='font-size: smaller;'>1</sup>
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Question 229:
In the reaction of oxygen with hydrogen to produce water, which of the following statements is true?
  • A One atom of hydrogen reacts with two atoms of oxygen to give one molecule of water
  • B Two atoms of hydrogen react with two atoms of oxygen to give two molecules of water
  • C One molecule of oxygen reacts with one molecule of hydrogen to give two molecules of water
  • D One molecule of hydrogen reaccts with two molecules of oxygen to give three molecules of water
  • E One molecule of oxygen reacts with two molecules of hydrogen to give two molecules of water
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Question 230:
Na2CO3 + 2HCI → 2NaCI + H2O + CO2. Using the above equation, what volume of carbondioxide, measured at s.t.p is liberated when 53g of sodium carbonate is dissolved in hydrochloric acid?
(1 mole of gas occupies 22.4 dm3 at s.t.p)
(Na = 23, C = 12, O = 16)
  • A 44.8 dm<sup style='font-size: smaller;'>3</sup>
  • B 11.2 dm<sup style='font-size: smaller;'>3</sup>
  • C 100.1 dm<sup style='font-size: smaller;'>3</sup>
  • D 3.0 dm<sup style='font-size: smaller;'>3</sup>
  • E 22.4 dm<sup style='font-size: smaller;'>3</sup>
View Answer & Explanation