Scientists have hypothesized that oxygen began to build up in the earth's atmosphere after the development of living things with the ability to
a. breathe air.
b. form tissues.
c. photosynthesize.
d. reproduce sexually.

c. photosynthesize.

Explanation:

It is believed that it was life itself that originated all this oxygen present on the planet and promoted the change in the composition of the earth's atmosphere. This change would have begun, according to paleontologists, when the ability to perform photosynthesis emerged during the evolution of living beings. Commonly associated with plants, the ability to produce oxygen is also common to bacteria such as blue algae, unicellular beings that live in the oceans and, despite their name, are more similar to bacteria than algae. The great virtue of photosynthesis is to convert sunlight and carbon dioxide into energy for metabolism. As a byproduct, oxygen is released.

1.consider the following balanced equation and answer parts a through. show calculations for each part.  

3 ag(s) + 4 hno3(aq) → 3 agno3(aq) + no(g) + 2 h2o(l)  

a. calculate the number of moles of agno3 produced by the reaction of 3 moles of ag with excess hno3. if the number to the left of the compound represents the number of moles of the compound which are present, then 3 moles of ag react with 4 moles hno3 to produce 3 moles agno3 (aq).

so the answer to a would be 3 moles.

b. calculate the number of moles of agno3 produced by the reaction of 108 grams of ag with excess hno3.  

i'm not sure how to plug in the grams of silver into an equation using moles to find how many moles are produced.

c. calculate the number of grams of agno3 produced by the reaction of 108 grams of ag with excess hno3  

d. calculate the number of moles of no produced as a byproduct of the reaction of 108 grams of ag with excess hno3.  

e. calculate the number of grams of no produced as a byproduct starting with 108 grams of ag and excess hno3.  

explanation: