Why must a container or system be closed for equilibrium to be established?

If you're dealing with gases, some of them could escape the container. Or, if you're dealing with liquids, there could be some outside factors playing in. In general, you need a closed system to observe a reaction accurately.

explanation:

i think option no d is the correct answer

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).