Answer:
The first evidence of helium was obtained on August 18, 1868 by french astronomer jules janssen.
Explanation:
For some time helium was believed to exist only in the sun. However in 1882, Italian physicist Luigi Palmieri detected helium on earth when analyzing lava from mount vesuvius after it erupted in that year.
Opportunity cost is the loss of other alternatives when one alternative is chosen. It represents the benefits an individual, investor or business misses out on when choosing one alternative over another. An example is when I choose my career path. The opportunity cost represents all the other career paths that I did not choose.
Answer:
a) It created construction jobs for thousands of workers.
Explanation:
