Question

11. Which one of the following contains the same number of atoms as 7 g

of iron?

(a) 4 g of aluminium (b) 4g of magnesium (C) 4g of sulphur

(d) 3 g of carbon (e) 4 g of calcium

Answer 1

4 grams of sulfur contains the same number of atoms as 7 g of iron

Step-by-step explanation:

The statement "same number of atoms" is the same as stating "the same numer of moles." Moles are a count of atoms/molecules/etc.

So let's convert the masses into moles. Take the mass of an element and divide that by its molar mass (g/mole) to obtain moles of that element.

See the attached worksheet for these calculations.

The 7 grams of iron represents 0.125 moles of iron. The worksheet tells us that 4 grams of sulfur is also 0.125 moles. Nothing else has that number.

7 g of iron contains the same number of atoms as 4 grams of sulfur.

[1 mole = 6.02x10^23 particles].