Explanation:
It is known that for
, ppm present in 1
are as follows.
1
= 0.494 ppm
So, 150
= 
= 0.15 
Therefore, calculate the equivalent concentration in ppm as follows.

= 0.074 ppm
Thus, we can conclude that the equivalent concentration in ppm at STP is 0.074 ppm.
Answer: an element, feature, or factor that is liable to vary or change.
"there are too many variables involved to make any meaningful predictions"
Explanation:
Answer:
B
Explanation:
This is because exothermic reactions occurs when bnds are formed, and involves the release of energy.
Endothermic reaction occur when bonds are broken,and involves absorption of energy.
The right answer is D - mass.