81. The density of water is maximum at (a) 20 ºC (b) 4 ºC (c) 0 ºC (d) -4 ºC UPPSC AE 12.04.2016 Paper-II Ans : (b) The maximum density of water occurs at 4 ºC because, at this temperature two opposing effects are in balance. In ice, the water molecules are in a crystal lattice that has a lot of empty space. When the ice melts to liquid water, the structure collapses and the density of the liquid increases. Thus, the density of water is a maximum at 4 ºC 82. A perfect gas at 27 °C is heated at constant pressure so as to triple its volume. The final temperature of the gas will be. (a) 81 °C ...
