I need help asap plz

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6

Which description best characterizes the motion of particles in a solid?

Light waves can move through , but they travel fastest when they move through a(n) .