Final answer:
The question is asking for the amount of sodium (Na) atoms in 0.5 L of water (H₂O). The answer is B. 166.5 NA.
Step-by-step explanation:
The question is asking about the amount of sodium (Na) atoms present in 0.5 L of water (H₂O). To calculate this, we need to know the molar mass of Na and the molar mass of water. The molar mass of Na is 22.99 g/mol, and the molar mass of water is 18.02 g/mol. Since 1 mole of Na atoms is equivalent to Avogadro's number (6.022 x 10^23) of Na atoms, we can use the molar mass of Na to calculate the number of moles of Na present in 0.5 L of water. With this information, we can then calculate the number of Na atoms present in 0.5 L of water.
Using 22.99 g/mol as the molar mass of Na, we can calculate the number of moles of Na in 0.5 L of water using the formula:
Moles of Na = Mass of Na / Molar mass of Na
The answer to the question is B. 166.5 NA, as 0.5 L of water contains approximately 166.5 NA (sodium) atoms.