The mass of magnesium oxide with the amount of substance 0.5 is

The molar mass of MgO is 40 g. 0.5 mol of oxide has a mass of 0.5 * 40 = 20 g

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.