Waec Chemistry Past Questions For Year 2002
Question 31
Calculate the mass of sodium hydroxide in 5.00 dm3 of a 0.125 mol dm-3 solution. [NaOH = 40 g mol-1]
- A. 0.0156 g
- B. 0.625 g
- C. 1.00 g
- D. 25.0 g
Question 32
Consider the following equation: Cr2O2-7(aq) + 14H+(aq) + 6e- → 2Cr3+(ag) + 7H2O(1). The oxidation number of chromium changes from
- A. -2 to + 3
- B. -2 to + 6
- C. +6 to +3
- D. +7 to + 6
Question 33
A visible change is observed when a strip of iron is placed in an aqueous solution of
- A. FeSO4
- B. ZnSO4
- C. CuSO4
- D. MgSO4
Question 34
Which of the following compounds will leave a metal residue when heated?
- A. Cu(NO3)2
- B. AgNO3
- C. K2CO3
- D. CaCO3
Question 35
CuSO45H2O can be obtained from an aqueous solution of copper (ll) tetraoxosulphate (VI) by
- A. evaporation to dryness
- B. using chromatography
- C. precipitation
- D. crystallization
