Please help I’m timed You label another 100-ml beaker "#2", place it in a tared balance, and determine its mass. A portion of the unknown liquid is added to the beaker
and the mass of the liquid and the container is recorded.
mass of the empty beaker: 74.205 g
mass of the beaker with unknown liquid: 136.840 g
Using the Law of Conservation of Mass, what is the mass of the added liquid?

it would be b. 6co2 + 6h2o --> c6h12o6 + 6o2

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