Solution:
1. Calculate the molar mass of SO4:
- Sulfur (S) has a molar mass of approximately 32.07 g/mol.
- Oxygen (O) has a molar mass of approximately 16.00 g/mol.
- Since there are four oxygen atoms in SO4, multiply the molar mass of oxygen by 4: 16.00 g/mol * 4 = 64.00 g/mol.
- Now, add the molar mass of sulfur and the molar mass of oxygen: 32.07 g/mol + 64.00 g/mol = 96.07 g/mol.

2. Calculate the molar mass of Na2SO4:
- Sodium (Na) has a molar mass of approximately 22.99 g/mol.
- Since there are two sodium atoms in Na2SO4, multiply the molar mass of sodium by 2: 22.99 g/mol * 2 = 45.98 g/mol.
- Add this to the molar mass of SO4 calculated earlier: 45.98 g/mol + 96.07 g/mol = 142.05 g/mol.

3. Calculate the percent composition of SO4 in Na2SO4:
- Divide the molar mass of SO4 (96.07 g/mol) by the molar mass of Na2SO4 (142.05 g/mol) and multiply by 100 to get the percentage: (96.07 g/mol / 142.05 g/mol) * 100 67.64%.

So, the percent composition of SO4 in Na2SO4 is approximately 67.64%.

1 mol of any substance = 6.022 × 10^23 particles
Use the formula
Number of Na+ ions = moles of NaCl × 6.022 × 10^23
Given:
Moles of NaCl = 0.949
Calculate
Number of Na+ ions = 0.949 × 6.022 × 10^23
Number of Na+ ions = 5.715 × 10^23
Answer:
5.72 × 10^23 Na+ ions

Write the balanced equation
4 NH3(g) + 5 O2(g) : 4 NO(g) + 6 H2O(l)
Determine the mole ratio
From the equation: 4 moles NH3 produce 4 moles NO + 6 moles H2O
Total moles of products per 4 moles NH3 = 4 + 6 = 10 moles
Calculate total moles for 1.20 moles of NH3
Total moles of products = (10 / 4) × 1.20
Total moles of products = 3.0
Answer: 3.0 moles of products are formed

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Solution:
The molar mass of sodium (Na) is approximately 22.99 grams per mole (g/mol).

Therefore, the mass of 1.00 mole of sodium is:

1.00 mol x 22.99 g/mol 22.99 grams

So, the mass of 1.00 mole of sodium is approximately 22.99 grams.

The molar mass of sulfur (S) is approximately 32.06 grams per mole (g/mol). This means that 1.00 mole of sulfur has a mass of approximately 32.06 grams.