MRI machines use extremely strong magnetic fields. These fields must be adjustable to produce high-quality images. What might these machines use to generate such a field?
A
electromagnets
B
permanent magnets
C
induced current

Which statement is true about a catalyst? a: a catalyst decreases the rate of the reaction. b. a catalyst is consumed during a chemical reaction. c. a catalyst lowers the activation energy of a reaction. d. a catalyst increases the reactant concentration during a reaction.