Me im ! which of the following is an indication of a chemical reaction? freezing melting release of heat all of the above

A__ is two or more substances that are together in the same place but are not chemically combined

Frictional forces acting on an object are often converted into energy, which causes the temperature of the object to rise slightly.

As we move from left to right across the periodic table, what is the general trend? a) atomic radii increase. b) electronegavitiy decreases. c) nuclear shielding increases. d) metallic character decreases.