Choose the electron configuration for sodium (Na) in both longhand notation and noble-gas notation. A link to the periodic table is provided for you. Longhand notation:

The teacher is mostly talking about the distillation of a mixture

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. 

When china's civil war resumed, the nationalists held an advantage because the nationalist had more soldiers  than the communist.

The answer would have to be  reduce human impact on the environment