Distilled water (H20) can be made from tap water by removing dissolved minerals and various other chemicals. How should each type of water be classified?

A. Tap water is a homogeneous mixture and distilled water is a pure substance,

B. Tap water is a heterogeneous mixture and distilled water is a pure substance,

C. Tap water is a pure substance while distilled water is a homogeneous mixture.

D. Tap water and distilled water contain hydrogen and oxygen, therefore they are both pure substances,

i believe the answer is true.

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.  

it is the minimum amount of material needed to sustain a fission reaction.

critical mass is the minimum amount of fissionable material that must be assembled for a sustained fission reaction to take place. although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction. if the conditions are such that the neutrons are lost at a faster rate than they are formed by fission, the chain reaction will not be self-sustaining.   at the point where the chain reaction can become self-sustaining, this is referred to as critical mass.