If the condition change such that there are 4 mil at 4 atm and at 270 K, what is the new volume?

Increases in temperature tend to decrease density since volume will generally increase. There are exceptions however, such as water's density increasing between 0°C and 4°C. Below is a table of units in which density is commonly expressed, as well as the densities of some common materials.

Explanation:

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.