Question

neutron - absorbing material
rods containing uranium
nuclear reactor
a power plant needs to slow down the fission reactions in its nuclear reactor. in which direction should the uranium - containing rods in the diagram be moved?
left
up
right
down

Explanation:

Step1: Understand the role of neutron - absorbing material

Neutron - absorbing material reduces the number of neutrons available for fission. To slow down fission reactions, more neutron - absorbing material should interact with the uranium rods.

Step2: Analyze the movement direction

Moving the uranium - containing rods up will increase their exposure to the neutron - absorbing material (as they move towards the neutron - absorbing rods which are above in the diagram).

Answer:

up