Antoine lavoisier found that mass was conserved in chemical reactions when he saw that a) heat was released in chemical reactions. b) the products differed greatly from the reactants. c) the mass of the products was the same as that of the reactants. d) the mass of the products were heavier than the mass of the reactants.

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explanation:

covalent bonds

consist of pairs of electrons shared by two atoms, and bind the atoms to fixed orientation and requre high energies to break them

ionic bonds

when two atoms differ considerably in their electronegativity, then one of the atoms will lose its electron to the other atom. this results in a positively charged ion(cation) and a negatively charged ion (anion)

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.