What is missing in the following nuclear equation?
99 tc → ? + 99 ru
43
44

A beta particle

Explanation:

A beta particle is simply a high energy electron that is emitted from the nucleus. It DOES NOT affect the mass number of radioactive element TC, but affects the ATOMIC NUMBER by increasing it by 1 in Ru.

Thus mass number 99 remain the same in TC and Ru, but Atomic number increases from 43 to 44 due to beta decay

So, a beta particle is missing

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

lysosome is this part of the cell is surrounded by a very thick outer membrane to protect the rest of the cell from its strong enzymes.