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.
Explanation:
We know that,
1 mile = 1609.34 m
We need to find how many meters are present in the 12.45 miles. To find it use unitary method as follows :
12.45 mile = 1609.34 × 12.45
12.45 mile=20036.283 meters
or

Hence, this is the required solution.
Electrons are responsible for the transfer of charge.
Answer:224
Explanation:
We should answer it with Stoichiometry
We say: 20 g H2× (1 mol/ 2g)× ( 22.4 lit/ 1 mol) = 224
Means: we have 20 grams and every 2g H2, equals to 1 mol of it and every 1 mol of H2, equals to 22.4 lit( because of STP)
hope you got this:)