(Q).
Fact 1: Temperature changing can cause phase changes.  Fact 2: Melting is the change of phase from a solid to a liquid.  Given the two facts above, answer the question "What can cause melting?" with the following options:  - Changing pressure  - Heat energy  - Water expanding  - Evaporation  - converting electricity to heat  - Increase in mass  - Temperature changing  - Chemical reaction
(A).
Temperature changing


(Q).
Fact 1: Insulated material can be used for keeping warm.  Fact 2: Wool and some of the new insulated fleece materials are good.  Given the two facts above, answer the question "What can be used to keep warm?" with the following options:  - hair  - eating steak  - wool  - fibers  - hats  - catching lobster  - fueling cars  - fur
(A).
wool


(Q).
Fact 1: All chemical reactions require activation energy to get started.  Fact 2: Chemical changes are a result of chemical reactions.  Given the two facts above, answer the question "What is required before a chemical change?" with the following options:  - kinetic energy  - energy usage  - activation push  - activation energy  - activation switch  - activation power  - Burning fuel and air  - Evaporation
(A).

activation energy