hard · Act science

Students dissolved a fixed mass of KNO_3 in 100 g of water and recorded the maximum amount that would dissolve (solubility) at several temperatures: Temp (^circC): 20, 30, 40, 50, 60 Solubility (g per 100 g water): 32, 46, 64, 85, 110 A separate sample held 75 g of KNO_3 dissolved in 100 g of water. As this sample is slowly cooled from 60 ^circC, at approximately what temperature will the first solid crystals begin to form?

1. Just below 60 ^circC, because 75 g already exceeds the 60 ^circC solubility
2. Between 40 ^circC and 50 ^circC
3. Below 20 ^circC, since 75 g stays fully dissolved at every listed temperature
4. Exactly 30 ^circC, where solubility is 46 g

Sign up free to see the explanation and track your rank →