Answer:
3.28 degree
Explanation:
We are given that
Distance between the ruled lines on a diffraction grating, d=1900nm=
Where 


We have to find the angular width of the gap between the first order spectrum and the second order spectrum.
We know that

Using the formula
m=1


Now, m=2





Hence, the angular width of the gap between the first order spectrum and the second order spectrum=3.28 degree
Answer:
It would take two half-lives which would be 130days
The substance has a half-life of 30 minutes. There has been two cycles that have occurred.
idk the last one
Explanation:
A substance made up of only one type of element