The formula for mole fraction is:
-(1)
The solubility of oxygen gas = 1.0 mmol/L (given)
1.0 mmol/L means 1.0 mmol are present in 1 L.
Converting mmol to mol:

So, moles of oxygen = 0.001 mol
For moles of water:
1 L of water = 1000 mL of water
Since, the density of water is 1.0 g/mL.


So, the mass of water is 1000 g.
Molar mass of water = 18 g/mol.
Number of moles of water = 
Substituting the values in formula (1):


Hence, the mole fraction is
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Answer:
Prokaryotes are unicellular organisms that lack membrane-bound structures, the most noteworthy of which is the nucleus. ... While prokaryotic cells do not have membrane-bound structures, they do have distinct cellular regions. In prokaryotic cells, DNA bundles together in a region called the nucleoid.
The number of grams in 1.70 moles of Ca(NO₃)₂ is 384.2 grams
<h3>How to determine the mass of Ca(NO₃)₂</h3>
The mole of a substance is related to it's mass and molar mass according to the following equation:
Mole = mass / molar mass
With the above formula, we can determine the mass of Ca(NO₃)₂ as illustrated below:
- Mole of Ca(NO₃)₂ = 1.70 moles
- Molar mass of Ca(NO₃)₂ = 40 + 3[14 + (16 × 3)] = 40 + 3[14 + 48] = 40 + 3(62) = 40 + 186 = 226 g/mol
- Mass of Ca(NO₃)₂ = ?
Mole = mass / molar mass
1.70 = Mass of Ca(NO₃)₂ / 226
Cross multiply
Mass of Ca(NO₃)₂ = 1.70 × 226
Mass of Ca(NO₃)₂ = 384.2 grams
Thus, the mass of 1.70 moles of Ca(NO₃)₂ is 384.2 grams
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Answer:
1.2 x 10⁵ moles Ag (2 sig. figs.)
Explanation:
1 mole any substance (elements or compounds) => 6.023 x 10²³ particles of specified substance
∴ 6.9 x 10²⁸ atoms Ag = 6.9 x 10²⁸ Ag atoms / 6.023 x 10²³ Ag atoms/mole Ag
= 1.145608501 x 10⁵ moles Ag (calculator answer)
= 1.2 x 10⁵ moles Ag (2 sig. figs.)