Conduction of Electricity in Water

Q.

Which of the two is a better conductor of electricity : drinking water (tap water) or sea water? Give reason for your answer.

Q.

Explain why, distilled water does not conduct electricity but tap water conducts some electricity.

Q.

Distilled water is a good conductor of electricity.

1. True
2. False

Q.

Question 10

Paheli had heard that rain water is as good as distilled water. So, she collected some rain water in a clean glass tumbler and tested it using a tester. To her surprise, she found that the compass needle showed deflection. What could be the reasons?

Q.

Distilled water does not conduct electricity. What substances can be added to distilled water in small amounts to make it a good conductor of electricity ? Why ?

Q. Question 6
Does pure water conduct electricity? If not, what can we do to make it conducting?

Q.

Does pure water conduct electricity? If not, what can we do to make it conducting?

Q. Why lime juice is a good conductor ?

Q. Explain all the different types of chemical effects of electric current.

Q. Why is salt added to tap water during electrolysis?

1. To decrease conductivity.
2. To increase conductivity.
3. To increase temperature.
4. To decrease temperature.

Q. Question 9
Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.

Q. The bulb in the circuit does not glow when pure water is used as solution. Which of the following can be added to water to make the bulb glow?

1. Salt
2. Sugar
3. Honey
4. Sand

Q.

Name the sources of electricity.

Q.

How would you classify lemon juice a good conductor or a poor conductor of electricity

Q.

What is a nickel metal hydride battery?

Q.

Why a switch is always connected to the live wire of the cable?

Q.

What effect does an electric current produce when flowing through a conducting liquid (or conducting solution) ?

Q.

Where is any electric circuit switches are connected?

Q.

Which of the following types of energy can be used to decompose water into its elements ?
(a) heat energy
(b) light energy
(c) chemical energy
(d) electrical energy

Q. Question 7
In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.

Q.

Even though it can split into ${\mathrm{H}}^{+}$ and ${\mathrm{OH}}^{-}$ ions, why cant distilled water transmit electricity?

Q. Carbon electrodes are immersed in water and electric current is passed through it. Which of the following statements is correct?

1. Oxygen bubbles will be formed at the electrode which is connected to the negative terminal of the battery.
2. Hydrogen gas will be formed at the electrode which is connected to the positive terminal of the battery.
3. No gas is formed at any electrode.
4. Hydrogen gas will be formed at the electrode which is connected to the negative terminal of the battery.

Q.

Pure water is non-conducting but acidified water is good conductor of electricity. Explain.

Q. Question 8
A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?

Q.

What happens if the switch is connected to the neutral wire?

Q.

A switch in a circuit is always connected in the.

1. Live wire

2. Earth wire

3. Neutral wire

4. Either (a) or (b)

Q.

Why it is advised to cut off the power supply and switch off all the electrical appliances at time of floods?

Q.

Classify the following change as physical or chemical:

Crystallization of sugar from its saturated solution.

Q.

On electrolysis, water splits into

1. Positively charged hydrogen ions and negatively charged oxygen ions

2. Negatively charged hydrogen ions and Positively charged oxygen ions

3. Hydrogen and oxygen atoms positive and negative charges respectively

4. Hydrogen and oxygen atoms negative and positive charges respectively

Q.

Baking of roti is a physical change

1. True
2. False