Question

A 4.17 g sample of a pure element contains 3.35 x 10^22 atoms. What is the element?​

Answer 1

Answer : The element is, Arsenic (As)

Solution : Given,

Mass of a pure element = 4.17 g

Number of atoms =
`3.35* 10^(22)`

First we have to calculate the moles of a pure element.

`\text{Number of moles of an element}=\frac{\text{Given atoms of an element}}{\text{Avogadro's number}}=(3.35* 10^(22))/(6.022* 10^(23))=0.0556moles`

Now we have to calculate the molar mass of an element.

Formula used :

`\text{Moles of an element}=\frac{\text{Mass of an element}}{\text{Molar mass of an element}}`

Now put all the given values in this formula, we get

`0.0556mole=\frac{4.17g}{\text{Molar mass of an element}}`

`\text{Molar mass of an element}=75g/mole`

Thus, the arsenic is the element which has molar mass 75 g/mole.

Hence, the element is, Arsenic (As)