How did oxygen (O2) get into Earth's atmosphere? How did oxygen (O2) get into Earth's atmosphere? It was captured from the solar nebula. It came from chemical reactions with surface rocks. It was outgassed from volcanoes. It was released by life through the process of photosynthesis.

Option (4)

Explanation:

The primitive atmosphere was comprised of lesser or no amount of oxygen. With the progressive time, primitive organisms appeared such as the primitive aquatic plants, algae, and cyanobacteria, that carried out the process of photosynthesis in the presence of sunlight, water, and CO₂, and in return produced the food and oxygen. This is how the rapid photosynthesis process led to the increasing amount of oxygen in the atmosphere that facilitates the growth and evolution of different life forms on earth.

Thus, the correct answer is option (4).

r just means there's a number of carbon in teh chain. for example rcooh means that after x number of carbon, the chain ends with cooh.

explanation:

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.