What do you always wear when working with chemicals or flying objects

Protective wear such as Goggles, Gloves, and possible a lab coat.

Safety goggles. a lab coat if available. and gloves.

29.1-12=17.1the answer is this one

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.