8.) A silver bar of metal has a volume of 5.4 cm3 and a mass of 32.6 g. Is the bar of metal aluminum? The
density of aluminum is 2.7 g/cm3.
a.) No, the density of this metal is 6.0 g/cm2 (light blue)
b.) No, the density of this metal is 0.17 g/cm2 (green)
c.) Yes, the density of the metal is 2.7 g/cm(yellow)

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2