How do convection currents form? A. When heated air expands, it becomes less dense, rises, and displaces cooler,
more dense air, which moves downward.
B. When heated air expands, it becomes more dense, falls downward, and displaces cooler, less dense air, which rises.
C. When cooled air contracts, it becomes less dense, falls downward, and displaces warmer, more dense air, which rises.
D. When cooled air contracts, it becomes more dense, rises, and displaces warmer, less dense air, which falls downward.

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o