The black "smoke" that flows out of deep ocean hydrothermal vents is made of insoluble metal sulfides suspended in seawater. of the following cations that are present in the water flowing up through these vents, which ones could contribute to the formation of the black smoke?
pb2+
mn2+
mg2+
cu2+
na+
li+
zn2+
fe2+
ca2+

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e