Which of the following elements is not likely to form bonds?
a. gold
b. oxygen
c. neon
d. mercury

Neon is very known to form bonds to other elements, Just like all noble gases, it is very non-reactive. So much so, that it doesn't form compounds with anything. It is non-reactive because it's shells are full. Because neon has two atomic shells, it needs two electrons in the first and eight to fill the second. On the far right-hand side of the periodic table is the group of elements called the noble gases. Atoms of these elements (e.g., helium, krypton, neon) have full outer electron shells. These atoms are stable and very rarely form bonds with other atoms. These atoms usually form ionic bonds with each other. All substances including neon demonstrate dispersion forces. They are the weakest type of intermolecular force since they are only transient, but even so their overall effect is sufficient to form a significant attraction between particles. Dispersion forces occur due to the random motion of electrons within the atom.

Explanation:

the answer is barium and copper bromide

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock