Brass gets discoloured in air because of the presence of which of the following gases in air?
a. oxygen
b. hydrogen sulphide
c. carbon dioxide
d. nitrogen

Always use significant figure rules. remember that these rules apply to all numbers that are measurements. a car travels 6 miles north, 3 miles east, and then 2 miles south. what is the distance traveled? a.7 b.11

Advances in technology have enabled scientists and researchers to better study the evolutionary relationships between species

For a comparative or experimental investigation, scientists often make a testable about a scientific question, and then they test it in the investigation. a.control b.hypothesis c.procedure d.system