15 g NiO is dissolved into enough water to make 800. mL of solution. What is the molar concentration of the solution? Report your answer with the correct number of significant figures.

0.25

Explanation: M = moles of solute / volume of solution (L)

First, you need to calculate the number of moles using the given mass and the molar mass.

15 g74.692 g/mol≈0.20 mol

Then, you can solve for molarity using the molarity equation. The answer should be reported to two significant figures.

M=0.20 mol/ 0.800 L = 0.25 M

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