What mass of oxide will be obtained by oxidation of 6 g of metal whose equivalent mass is 20 g / mol?

You can write the equation for the reaction of metal oxidation. In short, it looks like this.
M + O = MO
It turns out that one equivalent of oxygen or 8 g / mol is added to one equivalent of metal.
In grams, it looks like this. 20 + 8 = 28 (grams) And in our case we have 6 grams of metal.
And so the proportion must be decided.
20 (g) metal corresponds to 28 (g) oxide
6 (g) corresponds to X (g)
And then X = 28 x 6/20 = 8.4 (g)
Answer: As a result of burning 6 grams of metal, 8.4 grams of this metal oxide is formed.