The rate law for a reaction is found to be rate = k[X]3. By what factor does the rate increase if [X] is tripled?

petroleum? coal maybe?

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

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.