Réponse :
0.9 g de glucose
Explications :
Formule : m = C x V x M
C (concentration): 20mmol.L-1 = 20 x 10^-3 mol.L-1
V (volume): 250,0mL = 250,0 x 10^-3 L
M (masse molaire): C6H12O6
M(C): 12,0 M(H): 1,0 M(O): 16,0
= 12,0 x 6 + 1,0 x 12 + 16,0 x 6 = 180 g.mol-1
DONC
m = 20 x 10^-3 x 250,0 x 10^-3 x 180 = 0.9 g