H2 h2o h2o2 ch4 all four examples represent

molecules

Justification:

1) Given formulas: H₂, H₂O, H₂O₂, CH₄.

2) A molecule is the chemical combination of two or more atoms through covalent bonds.

3) Non-metals only can bond among them by covalent bond, i.e. by sharing electrons.

Two nonmetals cannot bond to each other in other way (ionic bonds) because any of them will not be willing to release an electron completely.

Since the two nonmetal elements just need a few more electrons to complete their respective valence electron shell, they will do it by sharing electrons instead of releasing them.

pla·gia·rism

/ˈplājəˌrizəm/

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noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.