I believe the answer is an explosion
The two most abundant elements in the universe are HYDROGEN AND HELIUM. Hydrogen is the most abundant element followed by helium.
Hydrogen is the lightest of all element and the first element to be formed, followed by helium which has just two atoms.
A. Protons neutrons and electrons.
Haha those three make up a simple Atom.
The answer is (3) Cu2O. Copper (I) has an oxidation state of +1 (that's what the "I" indicates). You can also think of this as copper (I) having a charge of +1. Oxygen has an oxidation state of -2 (that's just a rule you have to know), and you can think of it as oxygen having a charge of -2. You need oxidation numbers in a neutral compound to add up to 0 (or charges in a neutral compond to add up to 0), so you need two Cu to balance the O, which is Cu2O.
Steel is an alloy and consists of more than one element (mainly iron and carbon), therefore steel is a mixture.