Lab Skills Review 7A2013

1. The problem of an experiment is in the form of a ____.

• Question2. A ______ is an educated

guess to the problem of the experiment.

• Hypothesis

3.

4.The ___________ states whether your hypothesis is correct or incorrect.

• Conclusion5.What would make the results

of an experiment carried out by a research team valid?

• The experiment was repeated and the sample size was increased.

6.The _______ group does not contain the independent variable.• Control

7. What is measured is known as the ______ variable.• dependent

8. A new idea that is tested in a scientific experiment is known as the ________.

• hypothesis

9. To test the effect of hormones on plant growth, 6 potted plant seedlings of the same species were measured and then sprayed with a growth hormone. After 4 weeks of growth under ideal conditions, the plants were measured again.

a. How would you set up the control group?• There should be another group with 6 plants that DO NOT

receive water.b. Identify the independent and dependent variables.• Independent variable: Growth hormone• Dependent variable: Length of the seedling

c. Give 2 factors that must be kept constant.• The amount of water each plant receives.• The temperature the plants were kept.• The species of plant used.• The amount of soil in each pot.

10. You studied the effect of the amount of fish food on the mass of goldfish. One tank of goldfish is fed the normal amount of food once a day. A second tank of goldfish was fed twice a day. A third tank of goldfish was fed three times a day. The fish's mass was measured three times a week.a.State the problem. •What is the effect of the amount of fish food on the mass of goldfish?b. Give a possible hypothesis.•I think that feeding the goldfish three times a day will increase the mass of the goldfish the most.c. Identify the independent variable. •The amount of foodd. Identify the control group.•The group of goldfish that were fed once a day.

10. You studied the effect of the amount of fish food on the mass of goldfish. One tank of goldfish is fed the normal amount of food once a day. A second tank of goldfish was fed twice a day. A third tank of goldfish was fed three times a day. The fish's mass was measured three times a week.e. Identify the dependent variable. •The mass of the goldfish. f. Identify 2 controls (factors that must remain constant).•Amount of fish in each group•Temperature of the water•Amount of light the fish are exposed to•The original mass of the fish

11. An experiment was done in which the heart rate of water fleas were measured after being placed in water at different temperatures. a. IV

•temperatureb. DV

•Heart ratec. How would you label each axis on a line graph for this experiment?X axis = tempY axis = heart rate d. What would be a proper title for this experiment?The effect of temperature on the heart rate of water fleas.

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11. e. State the

relationship between the average water flea heart rate and water temperature.

As water temperature increases, the average water flea heart rate increases.

• Direct Relationship

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f. What is the average flea heart rate at 15ºC?

• 118 beats/min g. What is the

average flea heart rate at 30ºC?

• 240 beats/min

12. Problem: Does an electric motor turn faster if you increase the voltage?

a. IV• voltageb. DV• How fast the motor turnsc. 1 constant• Same motor

13. Problem: Does heating a cup of water allow it to dissolve more sugar?

a. IV• temperatureb. DV• How much sugar dissolvesc. 2 constants• Type of sugar, how fast they stir it

14. Problem: Does fertilizer make a plant grow bigger?

a. IV• Amount of fertilizerb. DV• growthc. 2 constants• size of pot, same type of plant,

amount of water, light

a. Identify the independent and dependent variables.• IV = amount of spring rainfall• DV = number of frogs in the pond

b. State the relationship between the number of frogs in the pond.• Direct relationship (as the amount of spring rainfall increases,

the number of frogs in the pond also increases)

c. How many frogs are present when there is 15cm of spring rainfall?

• 50 frogs

15.

16. You want to test which size soccer is easier to juggle with your feet. You test the size 3, size 4, and size 5 ball. You count the number of seconds the ball stays in the air for each trial. You allow yourself to use both feet, knees and head to juggle the ball.a. Identify the independent variable.

b. Identify the dependent variable.

The size of the soccer balls.

The number of seconds the ball stays in the air.

16. You want to test which size soccer is easier to juggle with your feet. You test the size 3, size 4, and size 5 ball. You count the number of seconds the ball stays in the air for each trial. You allow yourself to use both feet, knees and head to juggle the ball.

c. What can be done to increase the validity of the experiment. Repeat the experiment.

Use a larger sample size.

17. The results of one experiment carried out by a research team would be considered valid if1. the experiment had no control setup2. all the members of the research team came to the same conclusion3. the experiment had more than one variable4. the experiment was repeated and the same results were obtained each time

18. Why do scientists make graphs of data from experiments? 

1. to observe general trends and patterns in the data

2. to make the observed data more accurate

3. to prevent errors in measuring data 4. to help change the original data

tables

19. A new idea that is tested in a scientific experiment is known as a(an)

1. theory 2. hypothesis 3. inference 4. observation

20. Which statement about the use of independent variables in controlled experiments is correct?

1. A different independent variable must be used each time an experiment is repeated.

2. The independent variables must involve time.

3. Only one independent variable is used for each experiment.

4. The independent variables state the problem being tested.

21. An investigation is carried out to determine the effect of exercise on the rate at which a person can squeeze a clothespin.

In this investigation, the independent variable is the

1. control 2. exercise 3. rate of squeezing 4. number of participants

22. An investigation is carried out to determine the effect of exercise on the rate at which a person can squeeze a clothespin.

In this investigation, the dependent variable is the

1. control 2. exercise 3. rate of squeezing 4. number of participants

23. Which piece of equipment could be used to determine the mass of a frog?

a. triple beam balanceb.graduated cylinderc. beaker d.metric ruler

24. The basic unit of volume in the metric system is the

a.kilogram b.gallon c.liter d.mass

25. Mass is best defined as the

a.The amount of space an object takes up

b.density of an objectc. amount of matter in an

object d.weight of an object

26. To measure the volume of an irregular solid, a student can use

a. a triple beam balanceb. a beakerc. displacement in a graduated

cylinderd. a thermometer

27. The units for the volume of a solid is

a.mLb.mmc.Ld.cm3

28. The amount of space an object takes up is known as its

a.massb.densityc. volumed.matter

29. What is the definition of mass?• The amount of matter in an

object.

30. What is the name of the instrument used to measure mass?

• triple beam balance

31. What are the units used to measure mass?

• grams

32. Determine the cm length at each letter to the nearest tenth.

• g = 9.7 cm• e = 10.3 cm• b = 11.3 cm• j = 11.7 cm

• f = 12 cm• a = 12.5

cm• h= 12.95

cm

0 1 2 3 4cm

8mm

33. What is the length of the object in millimeters? Centimeters?

0.8cm

0 1 2 3 4cm

34. What is the length of the object in centimeters?

2.8cm

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0 100 200 300 400 500g

0 1 2 3 4 5 6 7 8 9 10

332.7 g332.7 g332.7 g332.7 g35. Mass 35. Mass = = 35. Mass 35. Mass = =

0 10 20 30 40 50 60 70 80 90 g100

0 100 200 300 400 500g

0 1 2 3 4 5 6 7 8 9 10

57.1 g57.1 g57.1 g57.1 g36. Mass 36. Mass = = 36. Mass 36. Mass = =

0 10 20 30 40 50 60 70 80 90 g100

0 100 200 300 400 500g

0 1 2 3 4 5 6 7 8 9 10

345.7 345.7 gg345.7 345.7 gg

37. Mass 37. Mass = = 37. Mass 37. Mass = =

38. Volume = ? Show all work

5.6 cm8.4 cm

6.4 cm

•V = L x W x H•V = 6.4 x 5.6 x 8.4•V = 301.1 cm³

3.2 cm

12.1 cm5 cm

39. Volume = ? Show all work.

•V = L x W x H•V = 5 x 3.2 x 12.1•V = 193.6 cm³

40. Measure the volume of the liquid to the right.

67mL

41. Measure the volume of the liquid to the left.21mL

42. Measure the volume of the liquid to the right.

43. Measure the volume of the liquid to the left.

2mL 49mL

44. What is the volume of this toy dinosaur?

0.8mL (5.6mL – 4.8mL)

45. What is the name of this method?

displacement

46. Volume of object = ?

V1 =11.5 mL

V2 = 20 mL

V = 20 –11.5

V = 8.5 mL

47. Temperature:

When using the Celsius scale:a. water freezes at

0°Cb. water boils =

100°Cc. human body temperature is

37°C

3 cm = _____ mm

15 cg = ____ mg

49 cm = ____ mm

103 cm = ____ mm

5 mm = _____ cm

19 mL = ____ cL

74 mm = ____ cm

158 mm = ____ cm

48. Convert the following measurements:

3 cm = 30 mm

15 cg = 150 mg

49 cm = 490 mm

103 cm = 1,030 mm

5 mm = 0.5 cm

19 mL = 1.9 cL

74 mm = 7.4 cm

158 mm = 15.8 cm

k h d u d c m

49. Frank has a paper clip. It has a mass of 9.2 g and a volume of 14.3cm3. What is its density? Show all work.

50. Frank also has an eraser. It has a mass of 3.3 g, and a volume of 1.5cm3. What is its density? Show all work.

• D = m = 9.2 g = 0.6 g/cm3 v 14.3cm3

• D = m = 3.3 g = 2.2 g/cm3 v 1.5cm3

51.a. Which layer has the highest

density?• Green layerb. Which layer has the lowest

density?• Yellow layerc. Imagine that the liquids have the

following densities: 10g/cm3 3g/cm3 6g/cm3 5g/cm3

Which number would go with which layer?

• Yellow = 3g/cm3.• Blue = 5g/cm3.• Red = 6g/cm3

• Green = 10g/cm3

52.Osmium is a very dense metal.

a. What is its density in g/cm3 if 50.00 g of the metal occupies a volume of 2.22cm3? Show all work.

D = mass = 50.00 g = volume 2.22 cm3

D = 22.5 g/cm3

b. Will this object float in water? Why or why not?

No, it will not float because it’s density is greater than the density of water. It will sink.

c. If you cut this object into 4 pieces what will be the density of each piece ?

22.5 g/cm3

53. Which diagram represents the liquid layers in the cylinder?(K) Karo syrup (1.4 g/mL)

(V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)

K

K

W

W

W

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V

V

K

A B C

54. What is density? Mass per unit volume

55. How is the density of an object measured? Density = mass/volume

56. What is the density of one cup of water?

1g/mL

57. What is the density of half a cup of water?

1g/mL

58. What is the density of a 100gram object with a volume of 20 milliliters?

5g/ml

59. The object above was cut into three pieces. What is the density of one of those pieces?

5g/ml

60. Explain why an object placed in a glass of water floats.

The object has a density less than the density of water (1g/ml).

61. Explain why an object placed in a glass of water sinks.

The object has a density more than the density of water (1g/ml).

62. Below is a list of the densities of different object. Will each one float or sink in water?

a. 0.38 g/cm3

b. 1.7 g/cm3

c. 1.2 g/cm3

d. 0.99 g/cm3

e. 100 g/cm3

float

float

sink

sink

sink