(optional) You are given nine pennies. One penny was minted in 1980 and the other eight pennies were minted after 1982. The 1980 penny weighs 3.0 grams; the other pennies have copper and weigh only 2.5 grams. Assuming the mint dates are illegible, devise a method usin the balance shown to determine the heavier 1980 penny in only two trials. 3. less

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

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~ trueboss72

gas

explanation:

smoke is the matter of a gas