Answer:
The product is significantly impure
Explanation:
In order to test for the purity of a specific sample that was synthesized, the melting point of a compound is measured. Basically speaking, the melting point identifies how pure a compound is. There are several cases that are worth noting:
- if the measured melting point is significantly lower than theoretical, e. g., lower by 3 or more degrees, we conclude that our compound contains a substantial amount of impurities;
- wide range in the melting point indicates impurities, unless it agrees with the theoretical range.
Since our compound is even 10 degrees Celsius lower than expected, it indicates that the compound is significantly impure.
The answer is 35,000 calories
The pH levels of acid rain are very acidic; in the range of 2.0-3.0, is not true for acid rain.
Answer: D
Explanation
Acid rain is termed for the rain which contains acidic precipitations.
The precipitations of acids are generally made up of sulfuring and nitric acid.
The sulfuric and nitric acids were formed by the chemical reaction occurring between the water, oxygen and other chemicals present in the atmosphere with the sulfur-di-oxide and nitrous oxide emitted in the atmosphere due to burning of natural resources, fossil fuels, etc.
The chemical reaction of these oxides with water, oxygen and other chemicals leads to formation of acids.
Some of the oxides are emitted from burning of natural resources while the major emissions occur from burning of fossil fuels.
Also the oxides react in atmosphere to form acids.
So the options (A),(B) and (C) are true for acid rain.
But the option (D) is not true as the acid rain is not much acidic in nature, as it is getting dissolved in water so the range of acidity is 4.2-4.4 and not 2.0-3.0.
Answer: The mass percent of carbon in acetylene is 92.31 %.
Explanation:
In 
, there are 2 carbon atoms and 2 hydrogen atoms.
To calculate the mass percent of element in a given compound, we use the formula:
Mass of carbon = 
Mass of acetylene = 
Putting values in above equation, we get:-
Hence, the mass percent of carbon in acetylene is 92.31 %.
The answer is 9. Calcium nitrate is made up
of 3 different elements that equal 9 atoms.
