Asolid substance was tested in the laboratory.
the test results are listed below.
• dissolves in water
• is an electrolyte
• melts at a high temperature
based on these results, the solid substance could be
(1) cu (3) c
(2) cubr2 (4) c6h12o6

Your answer is (2) CuBr2, which dissolves in water, is an electrolyte (sort of the same things except that an electrolyte not only dissolves but is attracted by opposite poles), and melts at high temperatures.

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.