What do helium (he), neon (ne), and argon (ar) have in common?
a. they have the same number of electron energy shells.
b. they are all halogens.
c. they have the same number of electrons.
d. they are all noble gases.

The answer is: D

Explanation:

A. They have the same number of electron energy shells.  Is false, all the elements are in different periods so, they have different number of lectron energy shells.

B. They are all Halogens.  No, is wrong, halogens are F, Cl ,Br

C. They have the same number of electrons.  is wrong, if they had the same number of electrons they must be they same element and they aren't the same.

D. They are all Noble gases. Yes, it's true they are noble gases, they are the first group in the periodic table from the right.

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.

the answer is barium and copper bromide