Consider the following properties: i) the red color of rubies is due to the presence of chromium ions. ii) objects made of silver become tarnished. iii) the boiling point of ethanol is 78◦c. which is/are chemical?

II) Objects made of silver become tarnished.

Explanation:

Physical properties are the properties which can be observed without changing identity of substance.

Chemical properties are the properties which describe how the substance changes into the different substance completely.

Boiling is an example of physical change in state of the substance. Color is also an example of physical property like boiling point and hence these are constants. The reason of the color is that the chromium ions shows certain colors as the electrons are excited due to absorption of the light. The tarnishing of the silver is an example of the chemical change which occurs due to the reaction of the silver with oxygen. This is also known as corrosion.

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).