Respuesta :

Answer:

2.70 M.  

Explanation:

Molar mass of MgO = 24.3 + 16 = 40.3.

A molar solution will contain 40.3g in 1 Litre.

So 800 mL of 1 molar solution will contain 0.8* 40.3 g MgO.

So the molarity of the given solution

= 87 / (0.8*40.3)

= 2.699 M.