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

Chromium is used to make objects shiny because it resists scratches well. This means that objects coated with chromium can stay looking shiny and new for a long time without getting easily scratched.

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.

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).

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

• 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!