Dry air is a mixture of nitrogen, oxygen, carbon dioxide etc.
air is a mixture of gases 78% nitrogen an 21% oxygen and other components.
<u>Answer:</u> The correct answer is Option 4.
<u>Explanation:</u>
Bromothymol blue, Bromocresol green and Thymol blue are the indicators which change their color according to the change in pH of the solution.
The pH range and color change of these indicators are:
- Bromothymol Blue: The pH range for this indicator is 6.0 to 7.5 and color change is from yellow to blue. It appears yellow below pH 6.0 and blue above pH 7.5
- Bromocresol green: The pH range for this indicator is 3.5 to 6.0 and color change is from yellow to blue. It appears yellow below pH 3.5 and blue above pH 6.0
- Thymol Blue: The pH range for this indicator is 8.0 to 9.6 and color change is from yellow to blue. It appears yellow below pH 8.0 and blue above pH 9.6
As, the highest pH of all the indicators is 9.6, so every indicator will appear blue above pH 9.6.
Hence, the correct answer is Option 4.
Answer: 
Explanation:
Depression in freezing point is given by:
= Depression in freezing point
i= vant hoff factor = 1 (for non electrolyte like urea)
= freezing point constant = 
m= molality
Weight of solvent (X)= 950 g = 0.95 kg
Molar mass of non electrolyte (urea) = 60.06 g/mol
Mass of non electrolyte (urea) added = ?
Thus urea was dissolved.
In oil and gas industry:
When crude oil get extracted from well, salt water and some other stuff needs to be removed before oil can be sued in the car
From own experience, I know that OsO4 is colorless, but Cr2O3 is actually a solid green from what I have seen. but I guess it could appear yellow-greenish.
