We plot the density of water as we heat a sample of ice till it melts, and keep increasing the temperature. Which of these statements is/are incorrect?
We plot the density of water as we heat a sample of ice till it melts, and keep increasing the temperature. Which of these statements is/are incorrect?
The correct option is B A glass of water is heaviest when the water is at 4∘C.
(a) We define density as mass per unit volume. From the graph, it is clear that water can have the same density at two different temperatures. This mean, 1 kg of water can have the same volume at two different temperatures. Given one of those temperatures is below 4∘C, and the other higher.
(b) This statement does not make much sense without information about volume. The "density” of water is highest at 4∘C. A glass of water weighing 200 gms at 90∘C will still weigh 200 gms at 4∘C, but a 1 cm3 sample from water at 4∘C will be heavier than the former.
(c) As we heat the sample of water we do not change the quantity or mass of the water. But given a fixed mass, since water reaches highest density at 4∘C, it will occupy the least volume, hence the water level will be lowest at 4∘C.
(d) The bottoms of all frozen lakes are at the same temperature of 4∘C. This is because as the cold temperature of the air starts cooling the water on the surface, the moment it reaches 4∘C, its density takes the highest possible value (for water), and settles at the bottom of the lake. You will encounter this phenomenon in greater detail in later units.
A glass of water is heaviest when the water is at 4∘C.
(a) We define density as mass per unit volume. From the graph, it is clear that water can have the same density at two different temperatures. This mean, 1 kg of water can have the same volume at two different temperatures. Given one of those temperatures is below 4∘C, and the other higher.
(b) This statement does not make much sense without information about volume. The "density” of water is highest at 4∘C. A glass of water weighing 200 gms at 90∘C will still weigh 200 gms at 4∘C, but a 1 cm3 sample from water at 4∘C will be heavier than the former.
(c) As we heat the sample of water we do not change the quantity or mass of the water. But given a fixed mass, since water reaches highest density at 4∘C, it will occupy the least volume, hence the water level will be lowest at 4∘C.
(d) The bottoms of all frozen lakes are at the same temperature of 4∘C. This is because as the cold temperature of the air starts cooling the water on the surface, the moment it reaches 4∘C, its density takes the highest possible value (for water), and settles at the bottom of the lake. You will encounter this phenomenon in greater detail in later units.
