The equation for the reaction at the anode during the electrolysis of concentrated sodium chloride solution is
- A. 2CI- (aq) → CI,sub>2(g) + 2e-
- B. 40H-(aq) → 2H2O(I) + O2(g) + 4e -
- C. Na+(aq) + e- → Na(s)
- D. 2H+(aq) + 2e- → H2(g)
A given fuel has an octane number of 100. This means that
- A. the knocking tendency of the fuel is low
- B. the fuel is a mixture of several hydrocarbons
- C. a large amount of alkanes is present in the fuel
- D. the fuel needs to be cracked before use
Determine the amount of electrons needed to deposit 6.4g of copper during the electrolysis of copper (ll) tetraoxosulphate (IV) solution [Cu = 64]
- A. 0.10 mole
- B. 0.20 mole
- C. 1.0 mole
- D. 2.0 mole
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
- A. L only
- B. l and ll only
- C. l,ll and lll only
- D. l, ll and lV only
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?
- A. V
- B. W
- C. X
- D. Z
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?
- A. V
- B. W
- C. X
- D. Z
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?
- A. Cu(s) + Zn2+(aq) →Cu2+(aq) + Zn(s)
- B. Cu(s) + Zn(s) →Cu2+(aq) + Zn2+(aq)
- C. Zn(s) + Cu2+(aq) →Zn2+(aq) + Cu(s)
- D. Zn2+(aq) +Cu2+(aq) → Zn(s) + Cu(s)
A reducing agent is expected to
- A. decolourize acidified KMnO4 solution
- B. decolourize acidified FeSO4 solution
- C. liberate CI2 from a chloride
- D. liberate CO2 from NaHCO3
Which of the following statements about an exothermic reaction is correct?
- A. the products have less heat content than reactants
- B. the system absorbs heat from the surrounding
- C. the activation energy is high
- D. the enthalpy change is positive
Sea shells contain mainly CaCO 3. Calcium oxide can be prepared from sea shells by
- A. adding dilute acid
- B. heating at a high temperature
- C. reduction with CO
- D. adding dilute NaOH(aq)
Which of the following processes involves neutralization?
- A. Hardening of oils
- B. Souring of milk
- C. Charring of sugar
- D. Liming of soil
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?
- A. the pH value was equal to 5 in each case
- B. the pH values of the HCI and H2SO4 solutions were equal
- C. their pH values added uo to 14
- D. the pH value of the CH3COOH was the highest.
What term is used to describe an oxide whose aqueous solution turns blue litmus red?
- A. Strong electrolyte
- B. Acid anhydride
- C. Amphoteric oxide
- D. Basic oxide
Substance Q reacts with cold water to form a solution which turns red litmus blue. Substance Q could be
- A. zinc
- B. phosphorus
- C. lead
- D. sodium
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
- A. l only
- B. ll only
- C. l and ll only
- D. ll and lll only
Which of the following salts can be prepared by reacting the metal with dilute H2SO4?
- A. CuSO4
- B. MgSO4
- C. BaSO4
- D. PbSO4
Bees inject an acidic substance when they sting. Which of the following chemical could be used to treat bee stings?
- A. CH3COOH
- B. NaHCO3
- C. C2H5OH
- D. H2O2
Which of the following acids is dibasic?
- A. Hydrochloric acid
- B. Trioxosulphate (IV) acid
- C. Dioxonitrate (lll) acid
- D. Ethanoic acid
Which of the following quantities is the same for one mole of Br2(l) and one mole of He(g)?
- A. Number of molecules
- B. Number of atoms
- C. Total mass of the particles
- D. Volume occupied at s.t.p
Which of the following statements about dative bonding is not correct?
- A. there is sharing of electrons
- B. one atom must possess a lone pair electrons
- C. each participating atom contributes one electron
- D. it can be formed between molecules
An element X with electronic configuration \(1S^22S^22P^63S^2\) combines with another element Y with the configuration \(1S^2S^22P^23S^23P^5\). What is the formula of the compound formed?
- A. X2Y5
- B. X2Y3
- C. XY3
- D. XY2