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Is there a picture To go with this?
Explanation:
Hydrogen H weight: 81
Non-metal
Hydrogen is the simplest element; an atom consists of only one proton and one electron. It is also the most plentiful element in the universe. Despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas on the Earth--it is always combined with other elements.
period 1 group 1
Hydrogen is easily the most abundant element in the universe. It is found in the sun and most of the stars, and the planet Jupiter is composed mostly of hydrogen. On Earth, hydrogen is found in the greatest quantities as water.
endothermic means it absorbs energy while exothermic means it releases energy. remember this.
Answer:
those are all physical changes and most physical changes can be undone like crushing a pice of metal you can flatten it back out you anwser is physical change
Explanation: