Why would you want to use a material that is not likely to undergo a phsical change for your stepping stone?

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

Modern weaponry has increased the number of deaths in wars and violent conflicts.

Aglow stick contains a glass vial with chemicals. when the glow stick is bent, the vial breaks and the chemicals react to produce a glow. a science student observes that a glow stick kept in the freezer glows for a longer duration than a glow stick kept at room temperature. what conclusion can be drawn based on the observation? be sure to note the outcome and test variables in the conclusion.