In 1950 the pH of the pond water was 8.2, but by 2000 the pH had decreased to 5.2. Which of the following changes would also be expected in the pond over the same time period?
I. Increased levels of dissolved oxygen.
II. Increased levels of heavy metals.
III. Increased number of fish species.

a) I only
b) II only
c) III only
d) II and III
e) I, II, and III

the answer is a. co2, this would be colder than the : )

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.