Shallow-sloped shield volcanoes are made from lava that A) is ...

[khang]

Shallow-sloped shield volcanoes are made from lava that
 
  A) is as runny as liquid water.
  B) has a medium viscosity.
  C) has a high viscosity.
  D) can have any viscosity.

Question 2

Why are infrared observations useful when observing extrasolar planets?
 
  What will be an ideal response?

[Tonny]

Answer to Question 1

B

Answer to Question 2

Because planets radiate mostly infrared radiation, it is possible to distinguish this from the parent star's light. This allows some spectral analysis of the atmospheres, letting us know of some molecules and atoms in planetary atmospheres, such as carbon dioxide, methane, hydrogen and sodium. In a few cases, water vapor has been detected, which is of particular interest.