A QUANTITY OF WATER AT 0 °C IS HEATED TO 30 °C. FOR EACH DEGREE RISE IN TEMPERATURE, ITS DENSITY WILL

• A. rise steadily
• B. fall steadily ✓
• C. fall and then rises
• D. rise and then falls

The answer to the question is: B. fall steadily

When a quantity of water at 0 °C is heated to 30 °C, its density will decrease. This is because water has its maximum density at around 4 °C. As the temperature of water increases from 0 °C to 4 °C, its density decreases. However, as the temperature continues to rise from 4 °C to 30 °C, the density of water also decreases.

The decrease in density with increasing temperature can be explained by the behavior of water molecules. At lower temperatures, water molecules are more closely packed and form a crystalline structure, leading to higher density. As the temperature rises, the thermal energy causes the water molecules to move more vigorously, disrupting the hydrogen bonds and causing the molecules to move further apart. This results in a decrease in density as the temperature increases.