Consider the following statements: Statement-I: Marine animals remain alive in winter and move near the bottom of lakes despite frozen water on the surface. Statement-II: The density of water is maximum at 4°C and water at the bottom of lakes remains warm in winter. Which one of the following is correct in respect of the above statements?
Both Statement-I and Statement-II are correct and Statement-II explains Statement-I.
Water shows anomalous expansion: as it cools, its density keeps increasing only up to 4°C, after which further cooling towards 0°C makes it less dense (ice is least dense and floats). So when a lake surface freezes in winter, the water at the bottom stays at about 4°C, the temperature of maximum density, which is warmer than the ice above. This relatively warmer bottom layer, insulated by the ice sheet, allows marine animals to survive and stay near the bottom. Both statements are factually correct, and Statement-II (density of water is maximum at 4°C, keeping the bottom layer warm) directly explains Statement-I (marine animals surviving near the bottom). The correct option is (a).
Important Questions from Thermal expansion
Thermal expansion of solids are:
A copper rod and a steel rod are to have lengths LC and LS, such that the difference between their lengths is the same at all ambient temperatures. If the coefficients of linear expansion of copper and steels are αC and αS respectively. The lengths are related to the coefficient of linear expansion as :
How much should the temperature of a brass rod be increased so as to increase its length by 1%?
Given: for brass α = 0.00002/°CA wooden wagon wheel has an outside diameter of 3750 mm. The iron tire for this wheel is deliberately made smaller so that it can be shrunk in place to be a tight fit. If the tire's inside diameter is 3737 mm at 20°C, the temperature to which it must be heated to fit over the wheel? The coefficient of linear expansion of the steel is 1.2 × 10-5/°C.
A cylinder of cross-sectional radius 1 cm and height 4 cm is heated from 0°C to 100°C. If the coefficient of linear expansion α = 4 × 10-4/°C, what will be the increase in the volume of the cylinder?
