The answer is D I hope this helps you !
Answer:
The elements in the reactants are the same as the elements in the products.
Explanation:
You can't have more or less elements or atoms, but you also can't just have the same number of atoms because then it could be different elements, which can't happen.
Answer:
Metal
Element: Calcium
Valency: 2
Explanation:
To find the element, let's use the periodic table. (Look below)
We already went past 3 shells, just need the 2 electrons after it.
Just skip to the 4th row and count 2 to the right
We end up at Calcium.
Calcium is a metal and we're also on the alkaline earth metals column.
Calcium will need to lose 2 electrons to reach stability, so the valency is 2.