To calculate the salinity in parts per thousand (ppt), you can use the formula:
\[ \text{Salinity (ppt)} = \left(\frac{\text{mass of salt (g)}}{\text{mass of salt (g)} + \text{mass of water (g)}}\right) \times 1000 \]
In this case, you have:
- Mass of salt = 146.3 g
- Mass of water = 520.4 g
Now plug the values into the formula:
\[ \text{Salinity (ppt)} = \left(\frac{146.3}{146.3 + 520.4}\right) \times 1000 \]
First, calculate the total mass of the sample:
\[ 146.3 + 520.4 = 666.7 \text{ g} \]
Now, calculate the salinity:
\[ \text{Salinity (ppt)} = \left(\frac{146.3}{666.7}\right) \times 1000 \approx 219.4 \text{ ppt} \]
However, looking at the answer choices provided:
- 28 ppt
- 2.8 ppt
- 0.28 ppt
- 280 ppt
The closest answer to 219.4 ppt is not listed, but "280 ppt" is the nearest option. Since there might be an interpretation or rounding discrepancy in the choices, the answer would be:
280 ppt.