Study and practice Chemistry past questions with answers and detailed explanations. Then test your knowledge using our interactive CBT practice platform and prepare confidently for your upcoming examinations.
Which of the following compounds has the same empirical formula as benzene?
AC2H2
BC2H4
CC4H6
DC6H12
View Explanation & Discuss
Question 1242
waec2003
The equation for the reaction at the anode during the electrolysis of concentrated sodium chloride solution is
A2CI-(aq) → CI,sub>2(g) + 2e-
B40H-(aq) → 2H2O(I) + O2(g) + 4e -
CNa+(aq) + e- → Na(s)
D2H+(aq) + 2e- → H2(g)
View Explanation & Discuss
Question 1243
waec2003
A given fuel has an octane number of 100. This means that
Athe knocking tendency of the fuel is low
Bthe fuel is a mixture of several hydrocarbons
Ca large amount of alkanes is present in the fuel
Dthe fuel needs to be cracked before use
View Explanation & Discuss
Question 1244
waec2003
Determine the amount of electrons needed to deposit 6.4g of copper during the electrolysis of copper (ll) tetraoxosulphate (IV) solution [Cu = 64]
A0.10 mole
B0.20 mole
C1.0 mole
D2.0 mole
View Explanation & Discuss
Question 1245
waec2003
Which of the following statements is/are correct about tin plating? l The electrolyte must be a soluble salt of tin ll. the objective to be plated is made the cathode lll. The anode is made of tin lV. The negative electrode dissolves
AL only
Bl and ll only
Cl,ll and lll only
Dl, ll and lV only
View Explanation & Discuss
Question 1246
waec2003
Five metals represented by the letters V to Z are arranged in order of their reactivity as shown . V>W>X>Y>Z.
Which of the metals is most likely extracted by the electrolysis of its fused chloride?
AV
BW
CX
DZ
View Explanation & Discuss
Question 1247
waec2003
Five metals represented by the letters V to Z are arranged in order of their reactivity as shown . V>W>X>Y>Z.
Which of the metals cannot displace Y from an aqueous solution of its salt?
AV
BW
CX
DZ
View Explanation & Discuss
Question 1248
waec2003
Consider the electrochemical cell represented below Zn(s)/Zn2+(aq)//Cu2+(aq)/Cu(s). Which of the following equations describes the reaction occurring in the cell?
ACu(s) + Zn2+(aq) →Cu2+(aq) + Zn(s)
BCu(s) + Zn(s) →Cu2+(aq) + Zn2+(aq)
CZn(s) + Cu2+(aq) →Zn2+(aq) + Cu(s)
DZn2+(aq) +Cu2+(aq) → Zn(s) + Cu(s)
View Explanation & Discuss
Question 1249
waec2003
A reducing agent is expected to
Adecolourize acidified KMnO4 solution
Bdecolourize acidified FeSO4 solution
Cliberate CI2 from a chloride
Dliberate CO2 from NaHCO3
View Explanation & Discuss
Question 1250
waec2003
Which of the following statements about an exothermic reaction is correct?
Athe products have less heat content than reactants
Bthe system absorbs heat from the surrounding
Cthe activation energy is high
Dthe enthalpy change is positive
View Explanation & Discuss
Question 1251
waec2003
Sea shells contain mainly CaCO 3. Calcium oxide can be prepared from sea shells by
Aadding dilute acid
Bheating at a high temperature
Creduction with CO
Dadding dilute NaOH(aq)
View Explanation & Discuss
Question 1252
waec2003
Which of the following processes involves neutralization?
AHardening of oils
BSouring of milk
CCharring of sugar
DLiming of soil
View Explanation & Discuss
Question 1253
waec2003
The pH of 0.50 mol dm-3 solutions of HCI, H2SO4 and CH3COOH were measured. which of the following statements about the values obtained is correct?
Athe pH value was equal to 5 in each case
Bthe pH values of the HCI and H2SO4 solutions were equal
Ctheir pH values added uo to 14
Dthe pH value of the CH3COOH was the highest.
View Explanation & Discuss
Question 1254
waec2003
What term is used to describe an oxide whose aqueous solution turns blue litmus red?
AStrong electrolyte
BAcid anhydride
CAmphoteric oxide
DBasic oxide
View Explanation & Discuss
Question 1255
waec2003
Substance Q reacts with cold water to form a solution which turns red litmus blue. Substance Q could be
Azinc
Bphosphorus
Clead
Dsodium
View Explanation & Discuss
Question 1256
waec2003
Which of the following solutions will give a precipitate with dilute tetraoxosulphate (V) acid? l. Lead (ll) trioxonitrate (V) solution ll. Barium chloride solution lll. Sodium chloride solution
Al only
Bll only
Cl and ll only
Dll and lll only
View Explanation & Discuss
Question 1257
waec2003
Which of the following salts can be prepared by reacting the metal with dilute H2SO4?
ACuSO4
BMgSO4
CBaSO4
DPbSO4
View Explanation & Discuss
Question 1258
waec2003
Bees inject an acidic substance when they sting. Which of the following chemical could be used to treat bee stings?
ACH3COOH
BNaHCO3
CC2H5OH
DH2O2
View Explanation & Discuss
Question 1259
waec2003
Which of the following acids is dibasic?
AHydrochloric acid
BTrioxosulphate (IV) acid
CDioxonitrate (lll) acid
DEthanoic acid
View Explanation & Discuss
Question 1260
waec2003
Which of the following quantities is the same for one mole of Br2(l) and one mole of He(g)?
