Protostars are less dense than other stars.
Explanation:
Protostars are very young ‘stars’ made from hydrogen clouds that are beginning to coalesce and collapse under their weight. The hydrogen has not even begun fusing. Therefore, they are mainly made of hydrogen which is the lightest element in the universe.
Stars, however, have begun fusing hydrogen to other heavier elements like helium, carbon, oxygen, and iron. The elements are much heavier than hydrogen making other stars much denser than protostars.
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Answer:
There are many errors possible while titrating the acid of an unknown concentration with a base like NaOH.
Main error that leads to the error in results is misreading of the end point volume .
End point is when the reaction between the analyte and solution of known concentration has stopped .
Sometimes Burette is not straight enough to read the volume of the end point. One way to misread the volume of burette is by looking at the burette volume at an angle .
From above , volume seems to be higher. Indicators are used to indicate the color change of the reaction. In Acid-Base titrations , indicators first lighten up then changes its color.
So, error may have occurred in wrongly judging of the end point by color change of the indicator .
Answer:
Explanation:
Types of Sources
There are four main types of air pollution sources: mobile sources – such as cars, buses, planes, trucks, and trains. stationary sources – such as power plants, oil refineries, industrial facilities, and factories. area sources – such as agricultural areas, cities, and wood burning fireplaces.
Answer:
Explanation:
Molal freezing point depression constant of butanol Kf = 8.37⁰C /m
ΔTf = Kf x m , m is no of moles of solute per kg of solvent .
mol weight of butanol = 70 g
235.1 g of butanol = 235.1 / 70 = 3.3585 moles
3.3585 moles of butanol dissolved in 4.14 kg of water .
ΔTf = 8.37 x 3.3585 / 4.14
= 6.79⁰C
Depression in freezing point = 6.79
freezing point of solution = - 6.79⁰C .
Answer: There are 0.006 moles of acid in the flask.
Explanation:
Given: 
= 21.35 mL, 
= 0.150 M
= 25.0 mL, 
= ?
Formula used to calculate molarity of 
is as follows.
Substitute the values into above formula as follows.
As molarity is the number of moles of a substance present in a liter of solution.
Total volume of solution = 
= 21.35 mL + 25.0 mL
= 46.36 mL (1 mL = 0.001 L)
= 0.04636 L
Therefore, moles of acid required are calculated as follows.
Thus, we can conclude that there are 0.006 moles of acid in the flask.
