Can an Adult Gold Dragon in Change Shape form use any of the following abilities?
Bite. Melee Weapon Attack
Claw. Melee Weapon Attack
Tail. Melee Weapon Attack
The adult gold dragon's Change Shape feature includes (DMG 114):
In a new form, the dragon retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.
Notably, its attack options are not on that list, but it does retain Shape Change, so that it can change back to dragon form.