CLASS 10 ICSE Chemistry - Practice paper 18

ICSE - PRACTICE PAPER 18

ELECTROLYSIS

a) Give one term for the following:

i) The decomposition of a chemical compound when electricity is passed through its aqueous solution or fused state resulting in the discharge of ions at respective electrodes.

ii) The electrolytic process in which impure metals are purified to pure metals.

iii) The process in which metals are extracted from their ores using electrolysis.

iv) Separation of ions of an electrovalent compound when dissolved in water.

v) Electrolytic deposition of a superior metal on the surface of a baser metal or article.

b) A, B and C are three water soluble compounds.

When their aqueous solutions are taken in the electrolytic cell and the key is on the following observations are seen.

If A is taken the bulb glows brightly, with B the bulb becomes dim but when C is taken the bulb does not glow.

Then choose the correct answer from A, B or C for the following statements.

i) The solution which contains molecules only.

ii) The solution which contains ions only.

iii) The solution which possesses ions and molecules.

c) If a compound of X(metal) and Y(non metal) is taken in fused state and electricity is passed through it then the ions of _______ migrate towards cathode and are __________ to X and deposits on the cathode where as Y is obtained at ____________.( cations, Anode, cathode, reduced, oxidized,X)

d) In electrolysis ___________ migrate to cathode and anions to __________. Anode________ electrons from anions where as cation gains electrons from __________. Cations are ___________ while anions are __________ to neutral atoms. (Cathode, gains, reduced, cations, anode, oxidized)

e) ____________  are responsible for the flow of current through the electrolytic solution. As we descend the electrochemical series containing cations, the tendency of the ions to get ___________ at the cathode increases. The _____________ the concentration of an ion in a solution, greater is the probability of its being discharged at its appropriate electrode. (reduced, free ions, oxidized, lower, higher, free electrons).

f) Here are some electrode reactions. State at which electrode these reactions take place.(anode/cathode).

Mention the change that the given ion/atom undergoes in each case.

i) Cu²⁺ + 2e^- à Cu

ii) Cu – 2e^- à Cu²⁺

iii) 2Br ^– – 2e^- à Br₂

g) Choose the correct answer for the following statements.

(SO₄^2-, Anode, Silver, cathode, OH^–, Iron, Copper)

i) The metal taken as anode during the electroplating of an article with Silver metal using Sodium argento cyanide.

ii) A metallic electrode which does not take part in an electrolysis reaction.

iii) The anion which is discharged with most difficulty.

iv) The oxidizing electrode.

h) ‘M’ is a metal which is above Hydrogen in the activity series of metals. Its oxide M₂O dissolves in water and forms corresponding hydroxide.

i) State whether the hydroxide is an electrolyte.

ii) Write the cathode reaction during its electrolysis.

iii) Write the product at anode when inert electrodes are used.

i) State your observations in the electrolysis of:

i) Fused Lead bromide using Graphite electrodes

Cathode:

Anode:

ii) Dil. Sulphuric acid using platinum electrodes

Cathode:

Anode:

iii) Copper sulphate solution using Copper electrodes

Cathode:

Anode:

j) Write balanced electrode reactions during the electrolysis of :

i) Fused Lead bromide using Graphite electrodes

Cathode:

Anode:

ii) Dil. Sulphuric acid using platinum electrodes

Cathode:

Anode:

iii) Copper sulphate solution using inert electrodes

Cathode:

Anode:

k) Give reason:

i) Iron is not used as anode in the electrolysis of fused PbBr₂.

ii) Electrolytic cell is made of Silica in the above process.

iii) Water is acidified with dil. Sulphuric acid before electrolysis.

iv) The blue colour of Copper sulphate solution does not fade when it is electrolysed using Copper electrodes.

v) Silver nitrate is a strong electrolyte but not used not used in the electroplating with Silver.

vi) In electroplating the article to be plated is always made cathode.

vii) Direct current must be used in electroplating.

viii) Aluminium is extracted by the electrolysis of its salt in fused state.