Question

The percentage by mass of Br in the compound

AlBr3 is closest to
(1) 10.% (3) 75%
(2) 25% (4) 90.%

Answer 1

What you have to do it find the percentage / solve it. Divide the mass by the entire mass.
239.7 ÷ 266.68 = 0.898 × 100 = 90% Br.

Answer 2

Answer: The correct answer is option(4).

Step-by-step explanation:

Molar mass of the aluminium bromide,
`AlBr_3=266.69 g/mol`

Atomic mass of bromine = 79.90 g/mol

Percentage of Mass of bromine in
`AlBr_3`:

`\% Br\text{ by mass}=\frac{\text{Atomic mass of Br}* \text{Number of Br atoms}* 100}{\text{Molar mass of }AlBr_3}`

`\% Br\text{ by mass}=(79.90 g/mol* 3* 100)/(266.69 g/mol)=89.97\%\approx 90\%`

Hence, the correct answer is option(4).