$(a)$ What temperature in Kelvin scale is equal to $50^{\circ} C$?
$(b)$ Describe an activity to show that the rate of evaporation increases with surface area.

(A) To convert Celsius to Kelvin,we use the formula: $T(K) = T(^{\circ}C) + 273.15$. Therefore,$50^{\circ}C = 50 + 273.15 = 323.15 K$ (or approximately $323 K$).
$(b)$ Activity: Take two containers,a narrow glass and a wide saucer. Pour an equal amount of water into both. Place them in the same environment for the same duration. After some time,observe the water level. The water level in the saucer will decrease more than in the glass,demonstrating that a larger surface area leads to a higher rate of evaporation.