When a substance dissolves, it undergoes a chemical change.
a. true
b. false

False.

Solubility is not a chemical property but rather it is a physical property. A physical property is one that can be observed or measured and does not change the composition or identity of a substance in the process.

When a substances dissolves, this is a change of its physical state and it is mostly reversible.  For example, salt can dissolve in water to form a solution called brine. This does not alter the chemical nature of salt. When the water evaporates, salt is left behind in its original state or form. In other words, that was a physical change and it was completely reversible.

answer is a

explanation:

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: