Before 1937, scientists had not found element 43. Chemists predicted the
properties of element 43. How was it possible for chemists to predict these properties?

it should be all of them because it asks if you included all of those in your answer

explanation:

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).