Answer questions 1-3 based on the following scenario.
Scientists tested the effect of a fertilizer on the growth of plants. They had 2 sets of plants, Group A which gets fertilizer, water and sun and Group B which gets only water and sun (but in equal amounts to Group A).
1. Explain how this scenario is a controlled experiment and identify the manipulated variable.
2. If the scientists only performed 1 experiment but it supported their hypothesis, why can it not be considered a theory?
3. The graph below was created showing the growth of the plant. How would you know that the y-axis is measuring the growth of the plant?
4. You make the following measurements of an object: 42 kg and 22 m3. What would the object's density be? Show your work for credit and include final units.
5. Explain why a chlorinated swimming pool water would be a homogenous mixture?
6. Both slicing a tomato and a chemical change such as burning toast cannot be reversed. However, why is slicing a tomato still considered only a physical change?
7. If an ice cube melts at 0oC but water also freezes at 0oC, what is the difference between melting and freezing in terms of (a) the energy involved in the phase changes and (b) particles of the substances during the phase changes?
For questions 8 - 9 use the following pictures:
8. Which picture(s) would best represent atoms in the gas of a neon sign? Explain why.
9. Which picture(s) would best represent a rock? Explain why.
10. If measurements of a gas are 75L and 300 kilopascals and then the gas is measured a second time and found to be50L, describe what had to happen to the pressure (if temperature remained constant).Include which law supports this observation.
11. Which statement matches the scientists to their research on atomic theory?
a. Dalton used gold foil; Bohr made the planetary model of atoms
b. Thomson used gold foil; Dalton believed atoms had no internal structure
c. Rutherford used gold foil; Thomson discovered electrons
d. Rutherford discovered electrons; Thomson made the planetary model of atoms
For question 12, use the following picture:
12. What element is this? How do you know?
For question 13, use the following picture:
13. The picture is a model of a nitrogen atom. What is incorrect about the atomic orbital arrangement of electrons in this model?
For questions 14 - 17, write an equation for the reaction of magnesium chloride and sodium oxide to produce magnesium oxide with sodium chloride.
14. Show the formulas of the reactants.
15. Show the formulas of the products.
16. Write the balanced the equation for this reaction.
17. What type of chemical reaction is this? How do you know?
18. When is an atom unlikely to react and form chemical bonds?
19. What is the order of the types of nuclear radiation from lowest to highest energy?
20. Which statement is false? Rewrite it so that it is true.
a. Fusion involves the combination of two smaller atoms into a larger atom.
b. Fission involves the splitting of an atom into smaller atoms.
c. Fission and fusion are two processes that release very little amounts of energy.