A glass tube has one end in a dish of mercury and the other end closed by a stopcock.The distance from the surface of the mercury to the bottom of the stopcock is 800 mm,as indicated by the meter stick shown in the drawing below.The apparatus is at 20°C,and the mercury level in the tube is the same as that in the dish.
-Which drawing best shows the approximate level of the mercury in the tube when the temperature of the entire apparatus is lowered from +20°C to -20°C?
A)drawing (1)
B)drawing (2)
C)drawing (3)
D)drawing (4)

Question

A glass tube has one end in a dish of mercury and the other end closed by a stopcock.The distance from the surface of the mercury to the bottom of the stopcock is 800 mm,as indicated by the meter stick shown in the drawing below.The apparatus is at 20°C,and the mercury level in the tube is the same as that in the dish. 
-Which drawing best shows the approximate level of the mercury in the tube when the temperature of the entire apparatus is lowered from +20°C to -20°C?
A)drawing (1) 
B)drawing (2) 
C)drawing (3) 
D)drawing (4)

Quizplus · Accepted Answer

When the temperature is lowered, the mercury contracts, causing the level in the tube to drop. Drawing (3) likely shows this lower level.

A Glass Tube Has One End in a Dish of Mercury