When raymond observes certain natural phenomena, he often forms ideas about their causes and effects. suppose that raymond surmises that leaves change color in autumn due to scarcity of sunlight. in order to test whether his idea is accurate, he must first construct a falsifiable that defines a clear relationship between two variables. raymond's next step is to that would isolate and test the relationship between the two variables. this task can be pretty daunting because raymond will need to identify and eliminate any variables that could confuse test results.

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

the answer is symmetrical : )