As our current atmosphere formed, the concentrations of various atmospheric gases fluctuated. match each gas with the explanation that best describes how its proportion changed during the evolution of the atmosphere.

Janette goes into an electronics superstore to buy a new computer. the salesperson works with her to find the right model, and she agrees to buy a new computer for $500 and a floor-model 18-inch monitor for $100. just when she is ready to pay, the salesperson walks away for a minute and then comes back to inform her that the monitor she was ready to purchase can't be sold for < $125. she agrees to the extra $25 even though they had initially agreed on the $100 selling price. janette has fallen for the technique of gaining compliance.