Test: Chemical Effects of Electric Current- 1 - Class 8 MCQ

When electrodes are immersed in water and electricity is passed through it, water undergoes electrolysis. The water molecules are split into hydrogen and oxygen gases. The hydrogen gas is released at the negative terminal (cathode), and the oxygen gas is released at the positive terminal (anode). Therefore, the bubbles formed on the positive terminal are oxygen gas.

Sea water contains small quantity of salt that allow the flow of electric current through them. Distilled water, alcohol and sugar solution do not contain ions or charge particles.

On electrolysis of water Oxygen bubbles are formed on the electrode connected to the positive terminal of the battery and hydrogen bubbles formed on the other electrode.

Formation of gas bubbles on the electrodes, change of colour of solution, deposition of metals on the electrodes are some of the chemical effects of electric current.

Sulphuric acid is added to the copper sulphate solution to make it more conducting.

In LEDs, the longer lead (wire) is always connected to the positive terminal. This is because LEDs are diodes, and they only allow current to flow in one direction. The longer lead is the anode (positive terminal), and the shorter lead is the cathode (negative terminal).

When electric current is passed through water, water dissociates into hydrogen and oxygen. Hydrogen is deposited over negative pole and oxygen is deposited over positive pole. Deposition of hydrogen and oxygen at different poles is visible in the form of bubbles.

The substance through which electric current can flow easily are called good conductor of electricity. Metals are good conductor of electricity.

Both the statement are correct and explains the assertion. Chromium avoids corrosion and increase the hardness thus increasing the life of the iron materials like rims and car parts. It can be decorative, provide corrosion resistance, ease cleaning procedures, or increase surface hardness.

When electric current is passed through water, water dissociates into hydrogen and oxygen. Hydrogen is deposited over negative pole and oxygen is deposited over positive pole. Deposition of hydrogen and oxygen at different poles is visible in the form of bubbles.

When electric current passes through a conducting solution, it causes chemical reactions. This is called electrolysis and the effect is the chemical effects of electric current. The chemical effect of electric current may cause the formation of gas bubbles at the electrodes, deposition of metal on the electrodes and change in colour of the solution.

The amount of current flowing through a conducting solution depends on the conductivity of the solution. More the conductivity, more current passes through the solution and vice-versa. Hence, the conductivity of liquid A is more than the conductivity of liquid B.

• When electricity flows through a liquid that can conduct it, interesting things can happen.
• Bubbles of gas might pop up, you might see some shiny metal appear, and even the color of the liquid can change.
• So, when an electric current passes through a conducting solution, it can make bubbles, create metal bits, and even change colors!

Tin cans are thin electroplated on iron. These tin cans are used to preserve food items. Because tin is less reactive than iron as it will prevent food from being poisoned.