The fact that glass breaks into irregular shapes and pieces when struck could be because:

>Glass is a crystalline solid.
>Glass is an amorphous solid.
>Glass has no bonds holding it together.
>Glass is neither a crystalline nor an amorphous solid.

Glass is an amorphous solid

Explanation:

Amorphous Solid is also known as Non-crystalline solid. Unlike crystalline solids in which its atoms/molecules has a definite and regular pattern and arrangement, amorphous Solid’s molecules has no regular arrangement.

This is the reason why when force is applied it breaks into irregular shapes due to the nature of its molecules irregular arrangement . Other examples of amorphous solids are rubber and plastic.

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.