Which of the following conditions must be met for a volume ratio to be created from a balanced chemical equation?

changing temperature and pressure
constant temperature and pressure
changing temperature and constant pressure
constant temperature and changing pressure

Constant temperature and pressure

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.