Answer:
b. Bacteria photosynthesizing dissolved carbon dioxide in oceans
Explanation:
The levels of oxygen that we know nowadays in the atmosphere have not been like this in the more distant past. In order for the oxygen to start building up and change the composition of the atmosphere, something needed to happen, and that something was the cyanobaceteria. The cyanobacteria was able to perform photosynthesis, so it started to use the dissolved carbon for it, while in meantime it was releasing oxygen in the atmosphere. As the cynaobacteria was growing in numbers, over the course of millions of years, it managed to propel enough oxygen in the atmosphere so that the other organism can start developing, thus changing the world forever.
It is our primary protection from strong UV-B electromagnetic radiation from the sun.
Answer:
no. of protons = 39
atomic number = number of protons = 39
number of neutrons = 51
element is Yttrium
Explanation:
given data:
number of electron is 39
mass of atom is 90
We know that atoms are neutral because +ve charged protons is equal to no of -ve charged electrons.
we know that:
atomic number is equal to number of protons,
and atomic mass is the summation of no. of protons and no. of neutrons
number of protons = number of electrons
from the data given:
a) No. of protons = 39 (since number of electrons = protons)
b) atomic number = number of protons = 39
c) number of neutrons = atomic mass - atomic number
= 90 - 39
= 51
d) element is Yttrium
Sa asya basta sa asya yan tia
