Which of these is an indication that a chemical reaction has occurred?

a.) formation of gas

b.) boiling of a substance

c.) melting of a substance

d.) freezing of a substance

The answer is probably c. xylem

Answerd. may include all of these are many definitions of bases: the  brønsted-lowry definition of acids and bases says that bases are proton acceptors.the arrhenius definition of acids and bases says that bases increase [oh⁻] in solution (thereby producing oh⁻ ions)the lewis definition of acids and bases says that bases donate electron pairs.therefore, the sensible answer is that a base may include all of the described characteristics.

Answer (b) supersaturation;