For snow to fall to the ground, the temperature must be cold both up in the clouds where snowflakes form, and down at ground level. If the air near ground level is too warm, the snow will melt on its way down, changing to rain or freezing rain. Moisture is needed to form clouds and precipitation.
Answer:
1: At temperatures below 542.55 K
2: At temperatures above 660 K
Explanation:
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In this case, according to the thermodynamic definition of the Gibbs free energy, it is possible to write the following expression:

Whereas ΔG=0 for the spontaneous transition. In such a way, we proceed as follows:
1:

It means that at temperatures lower than 542.55 K the reaction will be spontaneous.
2:

It means that at temperatures higher than 660 K the reaction will be spontaneous.
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a. They are both normally found as gases in the atmosphere. TRUE
That is correct, the oxygen and nitrogen are found in large quantities in the air around us.
b. They can be either liquids or gases. TRUE
Under certain temperatures any gas will transform into a liquid.
c.They turn from gas to liquid at the same temperature. FALSE
Oxygen it will pass into a liquid at -183 °C while nitrogen pass into a liquid at -195.8 °C.
d.They can be changed from gases to liquids by heating them. FALSE
The gases change to liquids by cooling them.
Density = mass/volume = 800/200 =4 g/cm^3