The average mass of an atom is calculated with the formula:
average mass = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2) + ... an so on
For the boron we have two isotopes, so the formula will become:
average mass of boron = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2)
We plug in the values:
10.81 = 0.1980 × 10.012938 + 0.8020 × mass of isotope (2)
10.81 = 1.98 + 0.8020 × mass of isotope (2)
10.81 - 1.98 = 0.8020 × mass of isotope (2)
8.83 = 0.8020 × mass of isotope (2)
mass of isotope (2) = 8.83 / 0.8020
mass of isotope (2) = 11.009975
mass of isotope (1) = 10.012938 (given by the question)
3.47 x
atoms of gold have mass of 113.44 grams.
Explanation:
Data given:
number of atoms of gold = 3.47 x
mass of the gold in given number of atoms = ?
atomic mass of gold =196.96 grams/mole
Avagadro's number = 6.022 X 
from the relation,
1 mole of element contains 6.022 x
atoms.
so no of moles of gold given = 
0.57 moles of gold.
from the relation:
number of moles = 
rearranging the equation,
mass = number of moles x atomic mass
mass = 0.57 x 196.96
mass = 113.44 grams
thus, 3.47 x
atoms of gold have mass of 113.44 grams
Answer:
The mass of an object is 0.6122 Kg
Explanation:
Given:
Acceleration = 9.8 m/s
Force = 58.8 N
To Find:
Mass of an object = ?
Solution:
We know that according to newtons 2nd law
Force is the product of the mass and acceleration
F= ma
where
F = Force
m = mass
a = Acceleration
Substituting the values,
58.8 = m X 9.8

m = 0.6122 kg
Answer:
Explanation:
A homogeneous mixture consists of one single phase while a heterogeneous mixture consists of two or more phases.