Front

Two circuits are shown. The light bulb lights up in only one of the circuits. What is the identity of X?

Back

calcium

Answer explanation

A metal can conduct electricity in solid state.

Calcium react with water to form calcium hydroxide which can then conduct electricity when in aqueous state.

Front

In which electrolysis experiment would there be no change in pH of the solution when inert electrodes are used? Options: aqueous copper (II) nitrate, aqueous silver sulfate, concentrated copper (II) chloride solution, concentrated potassium bromide solution

Back

concentrated copper (II) chloride solution

Answer explanation

at the cathode: copper (II) ions are discharge

at the anode: chloride ions are discharge (because the solution is concentrated)

Front

Electrolysis of dilute sodium chloride solution: x moles of electrons passed. Which statement is correct? Options: 6x dm³ of oxygen was collected at the anode., 6x dm³ of hydrogen was collected at the cathode., 12x dm³ of oxygen was collected at the cathode., 12x dm³ of hydrogen was collected at the anode

Back

6x dm³ of oxygen was collected at the anode.

Answer explanation

At the anode: hydroxide is discharge.

4OH^- -> O₂ + 2H₂O + 4e^-

Mole ratio of electron to oxygen is 4 : 1.

no of moles of oxygen = x/4

volume of oxygen = x / 4 x 24dm³ = 6x dm³

Front

The chloride of metal X is dissolved in water. A concentrated solution of this chloride is electrolysed using inert electrodes, Y and Z. X is above sodium in the reactivity series. In addition to chlorine, which gas is liberated and at which electrode?

Back

Hydrogen is produced at Z.

Answer explanation

Y is the anode and Z is the cathode.

Hydrogen is discharged at the cathode.

Front

When electrolysed using inert electrodes, which dilute solution would produce the greatest increase in mass at the cathode? Options: Aluminium sulfate, Copper (II) sulfate, Lead (II) nitrate, Silver nitrate

Back

Silver nitrate

Answer explanation

Ag just needs to gain 1 electron

Front

Which pair of metals X and Y will produce the highest voltage when used as electrodes in a simple cell?

Back

X: magnesium, Y: silver

Front

In an electrolysis experiment, the same amount of charge deposited 6.0 g of titanium and 7.0 g of iron. The charge on the iron ion was +2. What is the charge on the titanium ion? [A_r : Ti, 48; Fe, 56]

Back

+2

Front

The diagram shows a simple cell. Study the information given in the table. What could be the possible reading of S?

Back

1.5 V

Front

Direction of electron movement in a simple cell with silver and magnesium electrodes.

Back

magnesium to silver, through the wire

Front

The diagram shows a piece of red litmus paper connected to a battery. The litmus paper is soaked with concentrated sodium chloride solution. After a few minutes, what will be the colours at P and Q?

Back

P: white, Q: blue

Answer explanation

Chlorine discharge at the anode and bleaches the paper,

Hydrogen discharge at the cathode, lesser H+ ions and more OH- ions so more alkaline.