Alright so this is the big day i have more than 1 i am doing the cumulative exam and then i finish science so i need someone who can answer
them all for me.. i am putting in all my points for the right answer..

a substance is on its fifth half-life. which approximates the percentages of radioactive and stable isotopes, respectively?

-a-96.9%; 3.1%
-b-3.1%; 96.9%
-c-12.5%; 87.5%
-d-87.5%; 12.5%

rosa records the distance that a toy car rolls and the time it takes to cover the distance.

what scientific practice is this?

-a-collecting data
-b-asking a question
-c-providing explanations
-d-communicating results

chang makes the diagram below to compare gay-lussac’s law and charles’s law.
(vinn diagram with x in the middle)

which label belongs in the region marked x?

-a-involves changes in temperature
-b-has a constant volume
-c-shows an inversely proportional relationship
-d-does not involve pressure changes

how long will a radioactive isotope decay?

-a-until it reaches its half-life
-b-until there is no more material
-c-until it becomes a different, stable element
-d-until the neutrons are returned to the base element level

which sound is most likely the most intense?

-a-a whisper
-b-a rock concert
-c-normal speech
-d-the sound of rain

which characteristics are shared by electromagnetic and mechanical waves? check all that apply.(choose more than one)

{}both have a crest and a trough.
{}both move due to particles bumping into each other.
{}both can move through matter.
{}both occur as a result of a disturbance.
{}both are formed by charged particles.

which is a result of using a machine?

-a-the amount of work that is done is increased.
-b-the work input is less than the work output.
-c-both the force and the distance through which it acts increase.
-d-the distance through which a force acts increases, and the force decreases.

miles mixed two unlabeled solutions together. this caused a bad reaction, and a noxious gas was emitted. which describes what miles should do?

-a-he should use a fire blanket to cover his solutions.
-b-he should report the accident and leave the area.
-c-he should neutralize the reaction by adding water.
-d-he should pour the solution down the sink to stop the gas.

which statement best describes the explanatory powers of hypotheses and theories?

-a-a hypothesis does not provide an explanation but instead only predicts what may happen.

-b-a theory does not provide an explanation but instead only predicts what may happen.

-c-the explanation given by a theory is well tested and supported by many observations and hypotheses.

-d-the explanation given by a hypothesis is well tested and supported by many observations and theories.

which statement best describes a relationship amongst hypotheses, theories, and laws?

-a-a hypothesis is used to explain laws and theories.
-b-a law is used to explain a hypothesis and theories.
-c-a hypothesis combines several theories.
-d-a theory combines several hypotheses.