Which of the following statements is correct with respect to electron spin? a. the two electrons in one orbital must have opposite spin. b. the two electrons in one orbital must have the same spin. c. the two electrons in one orbital can have either opposite or the same spin. d. the two electrons in one orbital repel each other if they have opposite spin. e. the two electrons in one orbital attract each other if they have the same spin.

Select the correct value for the indicated bond angle in each of the compounds. o−o−oo−o−o angle of o3 90° 109.5° < 109.5° 120° < 120° 180° f−b−ff−b−f angle of bf3 180° < 109.5° < 120° 120° 109.5° 90° f−o−ff−o−f angle of of2 < 120° 120° 90° 109.5° 180° < 109.5° cl−be−clcl−be−cl angle of becl2 90° 109.5° 180° 120° < 109.5° < 120° f−p−ff−p−f angle of pf3 90° 109.5° < 109.5° 180° 120° < 120° h−c−hh−c−h angle of ch4 90° < 109.5° 180° 120° < 120° 109.5°

Achemical reaction is done in the setup shown , resulting in a change of mass. what will happen if the same reaction is done in a sealed container that is placed on the electronic balance?

If c + di is a point on the circle, then | c + di |=