Verified Answer :

Answer : 3.79 moles are in 987 grams of \(Ra(OH)_2\).

Solution : Given,

Mass of \(Ra(OH)_2\) = 987 g

Molar mass of \(Ra(OH)_2\) = 260 g/mole

Now we have to calculate the moles of \(Ra(OH)_2\).

Formula used :

\(\text{Moles of }Ra(OH)_2=\frac{\text{Mass of }Ra(OH)_2}{\text{Molar mass of }Ra(OH)_2}\)

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

\(\text{Moles of }Ra(OH)_2=\frac{987g}{260g/mole}=3.79moles\)

Therefore, 3.79 moles are in 987 grams of \(Ra(OH)_2\).

ajinems

The number of moles in 987 grams of Ra(OH)2 = 3.8 moles

Calculating number of moles

Ra = 226g

O= 16g

H = 1

Therefore molar mass of Ra(OH)2= 226+ (16+1)×2

= 260g/mol

The molar mass of Ra(OH)2 = 260g/mol

Thus means that 260g of Ra(OH)2 makes up 1 mole

Therefore, 987 g = X moles

Make X moles the subject of formula,

X mole = 987/260

= 3.8 moles

Therefore, the number of moles in 987 grams of Ra(OH)2 = 3.8 moles

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