Water exists in three different states (solid, liquid, gas) at different temperatures. According to the graph water exists in what state
at 50°C?

Water

Explanation: I don't see any graph attached, but water has a boiling point of 100C, which is where it would become gas, or water vapor. 0C is the freezing point of water, where it would become ice. Since 50C is in the middle, it would be considered liquid.

that tool would be a compass

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