Electrons are emitted from a conductor when the conductor is
a. exposed to weak light.
b. bombarded by high-speed electrons.
c. cooled rapidly.
d. subjected to a small voltage.

Electrons, the negatively charged particles that carry electricity in metals, can be ejected from the material if it is bombarded by a large number of high-speed electrons. This effectively, leads to some metallic electrons being "knocked" out of the material.

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.