Chemistry · Oct / Nov 2024 · Paper 41 · Question 4
0620
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The question as text
When magnesium nitrate is heated strongly, magnesium oxide is formed.
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4(a)(i)[2]
M1 +5
M2 +4
4(a)(ii)[1]
oxygen
4(a)(iii)[4]
M1 Mr of Mg(NO3)2 = 148
M2 mol of Mg(NO3)2 = 7.40 / 148 = 0.05(00) (mol)
M3 mol of NO2 = 0.05(00) × 4 / 2 = 0.1(00) (mol)
M4 volume of NO2 = 0.1(00) × 24 000 = 2400 (cm3)
4(b)[3]
M1 eight crosses in second shell of Mg
M2 six dots and two crosses in second shell of O
M3 ‘2+’ charge on Mg ion on correct answer line AND ‘2–’ charge on O ion on correct answer line
4(c)[2]
M1 two dot-cross pairs as a double bond
M2 four non-bonding electrons on each O
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