The overall charge of a formula unit for an ionic compound . Group of answer choices

A. is always zero (neutral)

B. it is always positive

C. is always negative

D. it may have any value

PLEASE HELPP
will give extra points

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

What produces wave a)sound b) heats c)transfer of energy d)vibrations

The gulf stream is a warm water current that flows away from the equator to northern europe. witch of these does it cause. a. crashes of warm and cool water in the ocean b. colder climates near the equator c. large waves on the cost of europe d. warm climates in northern europe