Compare the evaporation of a contained liquid with that of an uncontained liquid.

Evaporation in a closed container will come to a stop as soon as the vapor has saturated the space in the container , considering  the mass of the container and its content remains constant. On the other hand, evaporation from an open container will continue until all the liquid is gone, because the vapor disperses into the atmosphere and then is replaced with more vapor from the liquid. 

Which metal is less dense

the answer is true.

this statement is true.