Self-study
Large deposits of the rare mineral nahcolite formed in salty lakes 50 million to 52 million years ago during the Eocene epoch. ██████████ █████ █████ █████ ██ █████ ██████ █████████ ███ ████ ████ ████ ███ ██████████ ████████ ██ █████ █████ █████ ███ ███████ ██ ██████ ████████
Summary
Large deposits of a rare mineral, nahcolite, formed in salty lakes over 50 million years ago during a time in history called the Eocene epoch. Experiments revealed that, in salty water, nahcolite can form only when the atmosphere contains at least 1,125 parts per million of carbon dioxide.
Strongly Supported Conclusions
The atmosphere contained at least 1,125 parts per million of carbon dioxide sometime during the Eocene epoch.
10.
The statements above, if true, ████ ████████ ███████ █████ ███ ██ ███ ██████████
a
For most of ███ ████ █████ ███ ██████ ██████ ███ █████ ██ ██████ ███████ ██ ███ ██████████ ███ ████ █████ ████ ██ ███ ██████ ████ ██ ███ ██████ ██████
This comparative statement is not supported anywhere. The stimulus does not say anything about the relative levels of CO2 in the atmosphere during the Eocene epoch. It only implies that at some point in the epoch, the levels were high enough to form nahcolite.
b
Levels of carbon ███████ ██ ███ ██████████ ██████████ ███████ ██████ ███ ██████ ██████
There is no evidence to suggest that these levels fluctuated. For all we know, they could still be the same today. All we know is that the levels were enough to form nahcolite.
c
Lakes were more ██████ ██ ██ █████ ██████ ███████ ████ ███ █████ ██ ██████ ███████ ██ ███ ██████████ ███ ██ █████ █████ █████ ███ ████████
There is no support in the stimulus for whether a lake was more likely to be salty.
d
The atmosphere contained ██ █████ █████ █████ ███ ███████ ██ ██████ ███████ ██████ ██ █████ ████ ████ ██ ███ ██████ ██████
The stimulus says that this mineral was formed during the Eocene epoch and that it could only have formed when the atmosphere contained at least 1,1125 parts per million of carbon. This is not only supported, but it must be true.
e
No significant deposits ██ █████████ ████ ██████ ██ ███ ████ █████ ███ ██████ ██████
This requires an assumption that the level of CO2 in the atmosphere has changed since the Eocene epoch. There is no support for this in the stimulus.