Two beams of coherent light are shining on the same piece of ...

[Diane]

Two beams of coherent light are shining on the same piece of white paper. With respect to the crests and troughs of such waves, darkness will occur on the paper where:
 a. the crest from one wave overlaps with the crest from the other.
  b. the troughs from both waves overlap.
  c. the crest from one wave overlaps with the trough from the other.
  d. darkness cannot occur as the two waves are coherent.

Question 2

The sulfur hexafluoride molecule consists of one sulfur atom and six fluorine atoms. The atomic masses of sulfur and fluorine are 32.0 u and 19.0 u, respectively. One-half mole of this very heavy gas has what mass?
 a. 32 g
  c. 146 g
  b. 73 g
  d. 608 g

[k.lashomb]

Answer to Question 1

C

Answer to Question 2

B

[Diane]

Thanks for the timely response, appreciate it

[xthemafja]

Wow, this really help