Chemistry Past Questions and Answers

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

Question 22:

Which of the following is the electronic configuration of sodium?
(Atomic number of Na = 11)

A 1s² 2s²2p⁶ 3s²
B 1s² 2s²2p⁶ 3s² 3p1s² 2s²2p⁶ 3s¹
C 1s² 2s²2p⁶ 3s¹
D 1s² 2s²2p⁶ 3s^Â°
E 1s² 2s²2p⁶ 4s¹

Question 23:

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

Question 24:

Na₂CO₃ + 2HCI â†’ 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 dm³
B 11.2 dm³
C 100.1 dm³
D 3.0 dm³
E 22.4 dm³

Question 25:

When sodium nitrate dissolves in water, âˆ†H is positive. This means that?

A The reaction is catalysed
B The reaction is complete
C The reaction is exothermic
D The reaction is endthermic
E Sodium nitrate is highly soluble in water