Liquids conduct electricity - class-VIII

Solutions of acids and bases are generally good conductors of electricity.

Transfer of either heat or charge or an physical qty by touching is called conduction while rubbing against each other is know as friction. And charging by induction does not involve any contact with the surface whatever so.

Charge is an invariant quantity in special relativity; its magnitude does not change with velocity. Option C is also technically false as charge is a property of matter, but B is a more fundamental error regarding the definition of charge.

In water magnesium chloride ionizes to form ions and these ions conduct electricity. Sugar and iodine are non electrolytes. They do not dissociate into ions in aqueous solution. Hence, they do not conduct electricity.

Water is a weak electrolyte and is almost non conducting in nature as hardly any ions are present in pure water. However if impurities are present, then the conductivity will be high. In order to obtain the true value of the conductivity of water, these ions are removed by distilling the water several times. 

The best conductor of electricity is a 0.1 M solution of sulphuric acid as it is strong electrolyte and thus, ionises completely.

Pure water does not contain any salts or conducting impurities. Hence, it does not conduct electricity.

Passage of electric current may change the colour of a solution.
When an electric current is passed through a solution, a chemical reaction occurs. During this chemical reaction, coloured salts may form or may be consumed. This results in colour change for the solution.

While checking, your tester does not join its free ends for more than a few seconds. Otherwise, the cells of the battery will drain very quickly.

When the liquid (lemon juice) between the two ends of the tester allows the electric current to pass, the circuit of the tester becomes complete. The current flows in the circuit and the bulb glows indicating that lemon juice is a good conductor of electricity.

Air is a poor conductor of electricity.

LED glows even when a weak electric current flows through it. Also, even if the current is small, the deflection of the magnetic needle can be seen. Hence, tester using LED and magnetic effects of current can be used to detect a weak current.

When the liquid between two ends allow electric current, then the bulb of tester glows. 

When salt is dissolved in distilled water, we obtain salt solution. This is a conductor of electricity.

Though a material may conduct electricity, it may not conduct it as easily as a metal. As a result, the circuit of the tester may be complete and yet the current through it may be too weak to make the bulb glow.

While connecting to a circuit, the longer lead is always connected to the positive terminal of the battery and the shorter lead is connected to the negative terminal of the battery.

Tap water and vinegar are good conductors of electricity and hence, the compass needle could show deflection.

When the current through the circuit is too weak, the filament does not get heated sufficiently and the bulb does not glow.

When the liquid (vegetable oil) does not allow the electric current to pass, the circuit of the tester is not complete and the bulb does not glow.

It is not safe to carry out electrical repair works outdoor during rain because it contains small amounts of mineral salts naturally present in it. This water is thus a good conductor of electricity.

In LEDs, the longer lead is connected to the positive terminal and the shorter lead is connected to the negative terminal.

Salts, when dissolved in distilled water make it a good conductor.

LED stands for Light emitting diode.

LED is better than bulb to use in a tester as it glows even when a weak current passes through it.

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection due to magnetic effect . This magnetic effect is produced by electric current, passing through it.

Sugar solution will not make the bulb glow.

When electric current passes through the filaments of bulb, it starts emitting light due to heating effect of electric current.

Because if the liquid is conducting i.e electrolyte only then free ions will be present . Only in that case electric current will be able to produce chemical effect otherwise not.

Sea water is a good conductor of electricity but distilled water is not because sea water contains mineral salts.

Liquid $A$ is a better conductor than liquid $B.$

An acid in aqueous medium releases hydronium ions. Hence, it is able to conduct electricity. When sulphuric acid in aqueous medium is attached to a bulb in a beaker, current flows through it and lights the bulb.

A solution of $NaCl$ conduct electricity because in aqueous solution $NaCl$ dissociate into $Na^+$ and $Cl^-$ ions, which in solution are free to move and hence, conduct electricity.