A gas with a vapor density greater than that of air, would be most effectively displaced out off a vessel by ventilation.
The two following principles determine the type of ventilation: Considering the impact of the contaminant's vapour density and either positive or negative pressure is applied.
Consider a vertical tank that is filled with methane gas. Methane would leak out if we opened the top hatch since its vapour density is far lower than that of air. A second opening could be built at the bottom to greatly increase the process' efficiency.
A faster atmospheric turnover would follow from air being pulled in via the bottom while the methane was vented out the top. The rate of natural ventilation will increase with the difference in vapour density. Numerous gases that require ventilation are either present in fairly low concentrations or have vapor densities close to one.
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To know the melting or boiling points of substances is extremely important:
-In a Scientific Setting, it would help identify and separate unknown substances, as the melting or boiling points are unique for each compound, and their determination is useful for identifying and separating them.
-In an Industrial Setting, it would help engineers to know the storage temperatures of compounds. Some compounds if stored at temperatures above their boiling points will evaporate and when stored at temperatures under their melting points will solidify. In some cases this behavior is undesired and knowledge of boiling and melting points is important.
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Answer: the correct option is (C).
Explanation:
Covalent compounds have lower melting and boiling points due to presence of weak inter-molecular forces by which molecules are weakly associated to each other. Hence, melting and boiling of covalent compounds occurs at low temperatures.
Usually, Covalents compounds have following properties:
- They are brittle solids
- They do not conduct electricity
- They do not have rigid crystal structure.
- They exist in all states: solids, liquids and gases.
atom is indivisible particle and can be subdivided into smaller particles
