Question

Which of the following would show deflection in the compass needle, the moment you dip the free end of the tester?
A.Tap water, vinegar
B.Tap water, vegetable oil
C.Tap water, honey
D.Vegetable oil, honey

Answer 1

The compass needle would show deflection for those compounds or solutions that can conduct electricity. Only those compounds that can conduct electricity that contain ions, free ions.

Complete step by step answer:
Tap water has different kinds of cations and anions in it besides the water molecules. Commonly found cations include sodium ion, potassium ion, calcium ion, and magnesium ion. The common anions include chloride, nitrate, carbonate, etc. these ions are due to the salts found in tap water. As these ions are charged bodies, so they can carry electricity.
Hence, tap water is a conductor of electricity. Dilute acetic acid forms acetate ions and protons on dissociation in water. And those ions can conduct electricity as well. Hence acetic acid can also conduct electricity. But vegetable oil is a hydrocarbon and honey is a carbohydrate, both have covalent molecules and no ions are there. Hence, they are non-conductors of electricity.

So, the correct answer is option A, Tap water, vinegar.

Note:
Pure or distilled water is a non-conductor of electricity and that is because of the absence of ions in it. Only due to the presence of salts, tap water can conduct electricity. Current can be defined as the rate of flow of charge and the ions are the charge carriers or charge conductors.