Answer:
m = 671 grams
Explanation:
Given that,
No of moles, n = 4.9
Molar mass of Barium, M = 137 g
Mass divided by molar mass is equal to no of moles. It can be given by the formula as follows :

or
m = 671 grams
So, the total mass of the sample of Barium is 671 grams.
The given question is incomplete. The complete question is:
A brick has a mass of 4.0 kg and the earth has a mass of
Use this information to answer the questions below. Be sure your answers have the correct number of significant digits. What is the mass of 1 mole of bricks? Round your answer to 2 significant digits. How many moles of bricks have a mass equal to the mass of the Earth? Round your answer to 2 significant digits.
Answer: The mass of 1 mole of bricks is 
2.5 moles of bricks have a mass equal to the mass of the Earth
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number
of particles.
Mass of 1 brick = 4.0 kg = 4000 g (1kg=1000g)
Thus mass of 1 mole of brick or
bricks will be = 
The mass of 1 mole of bricks is 
Now
will correspond to = 1 mole of bricks
will correspond to =
2.5 moles of bricks have a mass equal to the mass of the Earth
Yes!!! The formula is Fe(No3)2
<h2>Answer:</h2><h2><em><u>If genetics or aging is the cause, nothing can prevent or reverse the process. However, treating graying hair could allow color pigmentation to return if the loss is due to a medical condition.</u></em></h2>