I believe the answer is 3 - He hypothesized that all substances can be broken down into a smallest part called the atom.
Answer:
1.07 g Ba
Explanation:
Hello there!
In this case, according to the definition of the Avogadro's number and the molar mass, it is possible to say that 6.022x10^{23} atoms of barium equal one mole, and at the same time, 1 mole equals 137.327 grams of this element; thus, it is possible to say that 6.022x10^{23} atoms of barium have a mass of 137.327 grams; therefore, it i possible for us to calculate the required mass in grams as shown below:

Best regards!
Answer:

Explanation:
1. Calculate the molar mass of Na₂SO₄

The molar mass of Na₂SO₄ is 142 g/mol.
2. Calculate the moles of Na₂SO₄

3. Calculate the mass of Na₂SO₄

Elements always exist as pair of atoms called molecules .
Explanation:-
- The material which has only one types of similar atoms called element .
- Ex:-Sodium,Carbon etc