Identify the missing substance in each of the following nuclear reactions.
137
156 Ba + Oye

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.

The velocity would be 2 

Aquantity of that isotope to decay to 1/2 of  its original value