Neutron Capture

_________ is formed in the air mostly by electron capture of potassium.

for the beta^(+) (positron) emission form a nucleus, there is another competing process known as electron capture. Electron form an inner orbit (say K shell) is captured by the nucleus and neutrino is emitted. Show that if beta^(+) emission is energetically allowed, electron capture is necessarily allowed but not vice -versa.

Thermal neutrons are

A small subatojmic particle was passed through large watger tank conatining Cd . The existence of this particles was inferred when two -gamma- rays were produced and a neutron was captured by Cd . The particle was:

Assertion: In u_(235) fission reaction neutrons are required to be slowed down. Reason: The probability of capture of slow moving neutrons in high for u_(235) .

Name the structure used By Hydra to capture to capture food.