Basic Chem help please?

Question

Hi---I was wondering if someone could look over my answers & make sure they are correct. If they are not; could you please tell me & help me fix it? Thanks to all. All help is greatly appreciated. =)

1. Indicate whether each statement is a fact, hypothesis or a theory.

_____ a. A micometer is larger than a nonometer ( I am thinking it is a fact--even though I have actually never heard of a "micometer" & a "nonometer"

_____b. Judy received a higher grade on the exam, b/c she studied longer. ( I think it is a theory)

2. Which one of the following is a chemical porperty of magnesium?

a. oxidized to produce white powder

b.has a density of 1.738 g/mL (I think it is this one)

c.is ductile

d. melts at 650 degrees C.

3. Which one of the following is a physical change?

a. bread toasting (I am thinking it is this one)

b. butter melting

c. an egg frying

d. an apple being digested

Answer 1

1)  fact

2) hypothesis

3) Mg+O2 produced white powder called MgO

4)b) butter melting (solid to liquid)

Answer 2

1.  Fact

2.  Hypothesis.

3.  I believe it's A.  The other 3 should be physical properties.

4.  B

A pretty effective way on remembering whether it's a physical or chemical change is to think about whether or not it can be reversed.

Once you toast bread, can you change it back to untoasted bread?  Can you unfry an egg?  Can you undigest an apple?  No.

But can you solidify melted butter?  Yes.

Answer 3

1. a. A micrometer is 10^-6 m and a nanometer is 10^-9 m, so the statement is a fact.

1. b.  This is a hypothesis, not a theory. Theories are widely accepted explanations based on a lot of observations over a long period of time.

2. a. is a chemical property; b,c,d are physical properties.

3. b. butter melting is the only physical change. With the others, there is a change in the chemical composition of the substances.

Answer 4

1 a and b are correct

2> the anser is C

3> B