Many hospitals, and some doctors\' offices, use radioisotopes for diagnosis and treatment, or in palliative care (relief of symptoms such as pain). some radioisotopes used in medicine are listed below. write the isotope symbol for each radioisotope. replace the question marks with the proper integers. replace the letter x with the proper element symbol.
a) iodine-131:
b) iridium-192:
c) samarium-153:

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

i think its 100.

hope this !

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.  

i believe the answer is 5,000