Question

Which describes a feature of the physical changes of all substances?

can dissolve in water
can conduct heat and electricity
rearranges atoms to form new substances
does not change the identity of a substance


What does the octet rule state that explains why atoms bond?

An atom bonds to have eight valence electrons to become stable.
An atom bonds to lose eight valence electrons to become stable.
An atom bonds to have eight valence electrons to become unstable.
An atom bonds to lose eight valence electrons to become unstable.


Which would show an example of how physical changes are reversible?

cutting a gold bar in two pieces and then putting the pieces next to each other
burning a match and then relighting it
melting tin and then cooling it into a mold
combining sodium and chlorine to make the new material of table salt



A gas is heated from 298 K to 367 K while its volume changes from 2.5 L to 3.9 L. If the initial pressure of the gas is 1.1 atm, what is the final pressure of the gas?

0.57 atm
0.87 atm
1.4 atm
2.1 atm


Suppose that a substance in a beaker is heated over a burner in a science lab. Which observation would most likely indicate that a chemical change has occurred in the substance?

If the substance is a liquid or solid, an increase in temperature would indicate a chemical change.
If the substance is a liquid, a change of some of the liquid to gaseous form would indicate a chemical change.
If the substance is a solid, a change of some of the solid to liquid form would indicate a chemical change.
If the substance is a liquid or solid, production of an odor would indicate a chemical change.

Answer 1

1) does not change the identity of a substance.
2) An atom bonds to have eight valence electrons to become stable.
3) melting tin and then cooling it into a mold.
4) 0.87 atm.
5) If the substance is a liquid or solid, production of an odor would indicate a chemical change.