Which of the following statements is/are correct? i. Principal energy levels are identified by the letters s, p, d, and f. ii. Principal energy levels appear in both the quantum mechanical model of the atom and the Bohr model of the atom. iii. In general, n = 1 is at lower energy than n = 2, and n = 2 is lower than n = 3, and so on. iv. The principal energy level is related to electron spin. a. i only b. iv only c. i and ii d. ii and iii e. iii and iv

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. 

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.