Which statement is true about the charges assigned to an electron and a proton?(1) Both an electron and a proton are positive.
2 answers:
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The mass of iron (III) oxide (Fe2O3) : 85.12 g
<h3>Further explanation</h3>Given
3.20x10²³ formula units
Required
The mass
Solution
1 mole = 6.02.10²³ particles
Can be formulated :
N = n x No
N = number of particles
n = mol
No = 6.02.10²³ = Avogadro's number
mol of Fe₂O₃ :
mass of Fe₂O₃ (MW=160 g/mol)
<u>Answer: </u>
A sample initially contained 150 mg of radon-222. After 11.4 days only 18.75mg of the radon-222 in the sample remained where 3 half-lives have passed
<u>Explanation:</u>
Given, the initial value of the sample, = 150mg
Final value of the sample or the quantity left, A = 18.75mg
Time = 11.4 days
The amount left after first half life will be ½.
The number of half-life is calculated by the formula
where N is the no. of half life
Substituting the values,
On equating, we get, N = 3
Therefore, 3 half-lives have passed.