Question

these two radioactive elements decay by electron capture (EC). Write the nuclear reactions for each decay including the formation of the daughter products:

a. 35 S + 0 e →
16 -1

b. 69 Sr + 0 e →
35 -1

Answer 1

It will make better sense if you write these like this since it is difficult to write superscripts and subscripts.
Atomic number/symbol/mass number, then add left numbers for final atomic number and add right numbers for the final mass number.
16S35 + -1e0 ==> 15P35 + neutrino + gamma ray
You do the other one. I can check your work if you wish.
https://en.wikipedia.org/wiki/Electron_capture

Answer 2

what is neutrino

Answer 3

Google neutrino. It has no charge and no mass but is a product of electron capture along with a gamma ray.