Which of the following statements is true? a. if an isotope of one element has the same atomic mass as another element, they will have the same properties. b. isotopes have the same chemical properties as the normal atom but different physical properties. c. isotopes have the same physical properties as the normal atom but different chemical properties. d. isotopes of the same element have the same number of protons and neutrons.

Hello!

I don't know a lot of this but after doing just a bit of research I think the answer is either A. or C. but I think it is A.

Hope it helps?

1) 0.5 mol.

2) 0.75 mol.

3) 16.8 L.

Explanation:

1) How many moles of Al react?

We can calculate the number of moles of Al (n) using the relation:

n = mass / molar mass,

Mass of Al = 13.5 g.

Molar mass mass of Al = 26.98 g/mol.

∴ The number of moles of Al (n) = mass / molar mass = (13.5 g) / (26.98 g/mol) = 0.5 mol.

2) How many moles of H₂ are produced?

It is a stichiometry problem.We should write the balanced equation of the reaction:

2Al + 6HCl → 2AlCl₃ + 3H₂.

It is clear that 2.0 moles of Al reacts with 6.0 moles of HCl to produce 2.0 moles of AlCl₃ and 3.0 moles of H₂.

Using the cross multiplication:

2.0 moles of Al → 3.0 moles of H₂, from the stichiometry,

0.5 mole of Al → ??? moles of H₂.

∴ The number of moles of H₂ are produced = (0.5 mole)(3.0 mole) / (2.0 mole) = 0.75 mol.

3) How many liters of H₂ are produced?

It is known that at STP, 1.0 mole of any gas occupies a volume of 22.4 L.

Using cross multiplication:

1.0 mole occupies → 22.4 L.

0.75 mole occupies → ??? L.

∴The number of liters of H₂ are produced = (0.75 mole)(22.4 L) / (1.0 mole) = 16.8 L.