Are protist heterotrophic or autotrophic

Which group of chordates does  notpossess true backbones?                 a.  birds      b.  frogs and toads      c.  lampreys      d.  crocodilians

Sarah is sitting at the top of the slide in the schools playground. which will increase sarah’s kinetic energy a- an additional child is added to the top of the slide. b- sarah is pushed and moves down the slide. c- sarah climbs down the ladder and off the slide. d- the ladder is moved to the other side of the yard.

A60-tooth gear is connected to a 72-tooth gear.if the smaller gear turns 12 times,how many turns does the larger gear make?