First of all if u know that 1 molecule of calcium hydroxide contain 2 hydrogen atom and 1 mole of calcium hydroxide contain 6.022*10^23 molecules of calcium hydroxide.
Hence 1 mole of calcium hydroxide contain 2*6.022*10^23 atom of hydrogen.
So 12 mole of calcium hydroxide contain =12*2*6.022*10^23. Atoms of hydrogen.
every action of has an opposite and equal reaction so we know that the rifle moved back toward her shoulder because the bullet that was fired out of gun was moving at a very high speed.
