When several cirque glaciers gauge an individual mountain summit ...

[justinmsk]

When several cirque glaciers gauge an individual mountain summit from all sides, a pyramidal peak known as a ________ results.
 
  A) col
  B) horn
  C) hanging valley
  D) artes

Question 2

How have scientists used isotopic analysis to determine the rise of atmospheric CO2 is mostly from the burning of fossil fuels?
 
  A) Since 14C is an unstable isotope, scientists have dated the atmospheric carbon to the period since the Industrial Revolution.
  B) Both coal and oil contain a high proportion of 14C. By analyzing, 14C/12C ratios, scientists have been able to determine the source based on this fact.
  C) The low proportions of 13C and 14C within atmospheric CO2 indicates the source is fossil carbon.
  D) 14C concentrations are much higher in urban areas than in rural areas, indicating fossil fuels must have a higher 14C/12C ratio than carbon from other sources.

[laurnthompson]

Answer to Question 1

B

Answer to Question 2

C