I would say compression or the absence of heat because heating a liquid makes it a gas<span />
None of the questions asked can be answered completely from the graph provided (GHG emissions: Direct, indirect and total Vs Year)
Reason:
1) Question A:<span>What caused a drop in GHG emissions around 2009?. This questions in pointing towards reason for drop of GHG emission around 2009. From the graph, it can be seen that there is a drop in GHG emission around 2009. However, information for reason for this drop is not available in graph.
2) Question B: </span>Did GHG emissions cause the melting of Arctic glaciers?. As mentioned earlier, the graph plotted provides information of GHG emissions: Vs Year. Information related to impact of GHG on environment is not available in graph.
3) Question C: <span>How much methane was emitted by homes between 1990 and 2000?. Graph provides information of direct and indirect emission for GHG. However, it lacks information about emission from residential or industrial sources.
4) </span>Question D: <span>Does industrial equipment release gases other than greenhouse gases?: Present study doesnot cover type of gases emitted from industrial equipment.
5) </span>Question E: <span>Which types of industries were included in the study?: Present graph has not specific information related to industries. </span>
Ammonia undergoes combustion with oxygen to produce nitric oxide and water. The volume of the oxygen required to react with 720 ml of ammonia is 900 ml.
<h3>What is volume?</h3>
Volume is the area occupied by the substance and is the ratio of the mass to the density.
At STP, 1 mole of gas occupies 22.4 L of volume
Given,
Volume of ammonia reacted = 0.720 L
The combustion reaction is shown as,

From the stoichiometry of the reaction, it can be said that,
L of ammonia reacts with
L of oxygen gas.
So, 0.720 L of ammonia will react with:

Therefore, the volume of oxygen required is 900 mL.
Learn more about volume here:
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Sodium is the reducing agent because a reducing agent is always the donor of electrons.
Answer:
Alchemy is a practice of making gold from other metals.
Explanation:
Alchemy is a method which is practiced by the ancient scientists of Europe, Africa and Asia trying to produced gold from other metals. This method was failed to produced gold from metals and all scientist suggested that metals can not be converted into gold. Greeks were the people who presented the theory of alchemy in the first few centuries of CE.