Question 1

In LEDs, the longer lead (wire) is always connected to the _______ terminal

Accepted Answer

In LEDs, the longer lead (wire) is always connected to the positive terminal. This is because the longer lead is the anode (+), and the shorter lead is the cathode (-).

Question 2

Tap water is a good conductor of electricity while distilled water is not because

Accepted Answer

Both tap water and distilled water differ in their conductivity due to the presence or absence of salts. Tap water contains dissolved salts and minerals, which facilitate the flow of electricity, making it a good conductor. On the other hand, distilled water lacks these salts and minerals, rendering it a poor conductor of electricity.

Question 3

When electrodes are immersed in water and electricity passed, the bubbles formed on the positive terminal is actually _______ gas.

Accepted Answer

When electricity is passed through water during electrolysis, water is split into hydrogen and oxygen gases. The bubbles formed at the positive terminal (anode) are oxygen, as oxygen is produced at the anode during the electrolysis of water.

Question 4

When electrodes are immersed in water and electricity passed, the bubbles formed on the negative terminal is actually _______ gas.

Accepted Answer

When electricity is passed through water during electrolysis, water is split into hydrogen and oxygen gases. Hydrogen gas is produced at the cathode (negative terminal), and oxygen gas is produced at the anode (positive terminal).

Question 5

Why do we add little dilute sulphuric acid to copper sulphate solution during electroplating?

Accepted Answer

Adding a little dilute sulphuric acid to the copper sulphate solution during electroplating increases the solution's conductivity, facilitating the electroplating process by allowing for a more efficient transfer of copper ions from the anode to the cathode.

Question 6

A coating of _________is deposited on iron to protect it from corrosion and formation of rust

Accepted Answer

Zinc is commonly used to galvanize iron, which involves coating the iron with a layer of zinc to protect it from corrosion and rust. This process is known as galvanization.

Question 7

Chromium plating is done on many objects such as car parts, bath taps, kitchen gas stove etc. Why?

Accepted Answer

Chromium plating is done to prevent corrosion and scratches.

Question 8

The process of depositing a layer of any desired metal on another material by means of electricity is called ___________.

Accepted Answer

Electroplating is the correct term for the process of depositing a layer of metal on another material using electricity.

Question 9

Some liquids are good conductors of electricity and some are poor conductors. Which one is a poor conductor?

Accepted Answer

Distilled water is a poor conductor of electricity because it lacks free ions, which are necessary for conducting electricity. In contrast, acidic solutions, alkaline solutions, and common salt solutions contain ions that facilitate electrical conductivity.

Question 10

Tin cans, used for storing food, are made by electroplating tin onto iron. Why?

Accepted Answer

Tin is less reactive than iron, which prevents the iron from rusting and keeps the food from becoming contaminated by the metal.

Quiz 1: Chemical Effect of Electric Current