What two things combine with oxygen to form ground-level ozone? A) NOx and ODS
B) CFCs and halons
C) NOx and VOC
D) HFCs and HCFCs

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

Consider the elements bromine and chlorine; which elements has a larger ionic radius ?

Which of the following are correct values for the ideal gas laws constant r