Determine the type of chemical reaction each of the following examples fit into: Mn (s) 2HBr (aq) ---> MgBr2 (aq) H2 (g)

Idon't understand what to put on the left lines i'm confused can anyone ?

Which of the following is true about the speed of light? it depends on the wavelength.

To find the work done, the force exerted and distance moved are multiplied. a couch is moved twice before you are happy with its placement. the same force was used to move the couch both times. if more work is done the first time it is moved, what do you know about the distance it was moved? a) when more work was done, the couch was moved the same distance. b) when more work was done, the couch was moved less. c) when more work was done, the couch was moved further. d) when more work was done, the couch wasn't moved at all.