Chemistry help please!!?

Question

1. Lord Kelvin described the concept of absolute zero temperature and the laws relating the change in thermal energy during chemical reactions. What type of chemist would he be considered today?
(Points: 3)
biochemist

inorganic chemist

physical chemist

organic chemist



2. When placed in a 100-mL square box, a substance takes the shape of the box and has a volume of 100 mL. When placed in a 50-mL circular tube, that same substance takes the shape of the tube and has a 50-mL volume. In which of the following states is the substance?
(Points: 3)
solid

liquid

gas

plasma



3. Which of the following terms describes cinnamon sugar?
(Points: 3)
compound

element

pure substance

mixture



4. Which of the following separation methods is used to separate plant pigments?
(Points: 3)
chromatography

simple distillation

fractional distillation

filtration



5. Jim, Jill, Robert, and Kim each run paper chromatography on an unknown aqueous mixture. Jim gets a red band and blue band, Jill gets a yellow band, Robert gets a green band, and Kim gets a red band. Which student had more than one substance dissolved in the water?
(Points: 3)
all of them

Jill

Jim

Kim



6. A chemist tests the quality of a brand of soft drink. Which of the following branches of chemistry might the chemist use?
(Points: 3)
inorganic chemistry

physical chemistry

analytical chemistry

organic chemistry



7. When you crush a first-aid pack for an injured athlete and the pack gets cold, which of the following is true?
(Points: 3)
A physical change has occurred, with energy being absorbed.

A chemical change has occurred, with energy being given off.

A physical change has occurred, with energy being given off.

A chemical change has occurred, with energy being absorbed.



8. A substance undergoes a change. Which of the following indicates that the change was a physical change?
(Points: 3)
Heat energy was given off.

The molecules of the substance changed.

The substance changed color.

The substance changed shape.



9. The air temperature surrounding an icy windshield is 0�C.The driver turns on the defroster and the ice melts. Which of the following is true?
(Points: 3)
The ice absorbed chemical energy to produce a chemical change.

The ice absorbed heat energy to produce a chemical change.

The ice released heat energy to produce a physical change.

The ice absorbed heat energy to produce a physical change.



10. Stacy runs a paper chromatography experiment using the same ink, but two different solvents. Using solvent A results in the ink separating into three bands, but solvent B does not carry the ink away from the original spot. Which of the following could explain the results?
(Points: 3)
Solvent B was not a good mobile phase because it could not dissolve the ink.

The ink was a pure substance and dissolved in both solvents.

The ink was a mixture, but only in solvent A.

Solvent A was not a good mobile phase because it could not dissolve the ink.



11. A prospector pans for gold in a stream. Which of the following best describes what is in her pan when he scoops up part of the streambed?
(Points: 3)
compound

element

pure substance

mixture



12. You have three molecules of sodium bicarbonate (formula: 3 NaHCO3). Which of the following is true?
(Points: 3)
The number of carbon atoms (C) is three times greater than the number of hydrogen atoms (O).

The number of oxygen atoms (O) is less than the sum of the sodium (Na), hydrogen (H), and carbon (C) atoms.

The number of oxygen atoms (O) is greater than the sum of the sodium (Na), hydrogen (H), and carbon (C) atoms.

The number of sodium atoms (Na) equals the number of carbon atoms (H).



13. An unknown substance undergoes a chemical change when it is heated. Which of the following statements is true?
(Points: 3)
The types of atoms before and after the change are the same, so the substance is a compound.

The types of atoms before and after the change are the same, so the substance is an element.

The types of atoms before and after the change are different, so the substance is a compound.

The types of atoms before and after the change are different, so the substance is an element.



14. Which of the following represents an element?
(Points: 3)
N2

H2O

CO

CO2



15. Steve, Sarah, Richard, and Kate each run paper chromatography on unknown liquids. Steve gets a red band and a blue band, Sarah gets a yellow band and a red ba

Answer 1

Best Answer - Chosen by Asker

1) physical chemist.
2) gas
3) mixture
4) chromatography
5) Jim
6) analytical chemistry
7) A chemical change has occurred, with energy being absorbed.
8) The substance changed shape.
9) The ice released heat energy to produce a physical change.
10) Solvent B was not a good mobile phase because it could not dissolve the ink.
11) mixture
12) The number of sodium atoms (Na) equals the number of carbon atoms (H).
13) The types of atoms before and after the change are different, so the substance is a compound
14) N2

Asker's Rating:

Asker's Comment:

thank you