An element weighing 9.6 g interacts with 12.8 g of oxygen, forms an oxide EO, which element is this?

Let E be an unknown element that has a valence of 2 and can form oxide EO.

Let’s write the reaction equation:

2E + O2 = 2EO

Let’s find the amount of substance E:

v (E) = m (E) / M (E) = 9.6 / M (E) (mol).

Let’s find the amount of oxygen substance:

v (O2) = m (O2) / M (O2) = 12.8 / 32 = 0.4 (mol).

According to the reaction equation, 2 mol Oe reacts with 1 mol O2, therefore:

v (E) = v (O2) * 2,

9.6 / M (E) = 0.4 * 2,

M (E) = 12 (g / mol), which corresponds to the element carbon (C).

Answer: carbon (C).