The graph shows the solubility of several different salts in water, across a range of temperatures. According to the
graph, which salt can dissolve at a concentration of about 60 g/100 cm3 of water at 40 degrees Celsius?

A) sodium nitrate
B) sodium chloride
C) potassium iodide
D) potassium nitrate

Explanation:

The attached graph with a green and a red arrow facilitates the understanding of this explanation.

To read the solubility on the graph, you can start with the temperature, on the x-axis.

The red vertical arrow shows how, departing from the 40ºC temperature on the x-axis, you intersect the solutibility curve of sodium chloride at a height (y-axis) corresponding to 60 g/100cm³ of water (follow the green horizontal arrow).

Hence, sodium chloride is the salt that can dissolve at a concentration of about 60g/100cm³ of water at 40ºC.