When an oxygen atom forms an ion, its gains two electrons. what is the electrical charge of the oxygen ion? -1 -2 +2 +1

An oxygen atom has 6 valence electrons and 8 electrons in total. Electrons have a negative charge. So when it gains 2 more electrons it becomes stable because of the octet rule. So it has a negative charge of 2. The answer is -2

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.