Adding a secondary concave lens of carefully chosen different ...

[j.rubin]

Adding a secondary concave lens of carefully chosen different glass to the primary lens on a refractor allows
 
  A) chromatic aberration to be reduced.
  B) more light to be gathered.
  C) greater magnification.
  D) X-rays to be focused.
  E) effects of atmospheric turbulence to be reduced.

Question 2

Main sequence stars are fusing hydrogen into helium in their cores.
 
  Indicate whether the statement is true or false

[Li Jun]

Answer to Question 1

A

Answer to Question 2

TRUE