Plz if you !
a and c are compounds. substance d is an element.
b and d are compounds. a and c are elements.
b is a compound, a, c and d are all elements
a and c are elements. substance d is a compound.

The answer to your question is: A and C are elements. Substance D is a compound.

Explanation:

We know that A and C cannot be broken down into anything simpler then we conclude  that they are elements.

Also know that B is composed by A and D and are not chemically bonded, so we conclude that B is a mixture

Finally, D can be decomposed into A and C, so it's a compound.

The only possible answer is the last one.

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).

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