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Tori - 8th Grade Science > Final Exam > Flashcards

Final Exam Flashcards

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1
Q

A group of students is investigating whether aluminum is a better thermal conductor than steel. The students take an aluminum wire and a steel wire of the same length and diameter. They put equal lengths of wax on one end of each wire and dip the other end into a beaker of hot water. The length of wax left on the wires after 10 minutes is shown.

Experimental Observations
Aluminum Steel
Original length of wax 2.5 cm 2.5 cm
Length of wax after 10 minutes 1.2 cm 1.8 cm

Which steps should the student take next?

A

Analyze the data

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2
Q

What is mass per unit volume called?

A

Density

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3
Q

Read the list of substances.

Wood, Iron, Sugar, Glass, Salt

Which substances are highly soluble in water?

A

Sugar and Salt

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4
Q

What can be answered with science?

Questions that are non-testable
Questions about things that can be measured
Questions that ask about an opinion
Questions that ask about a moral value

A

Questions about things that can be measured

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5
Q

Matt did an experiment to study the solubility of two substances.
He poured 100 mL of water at 20 °C into each of two beakers labeled A and B.
He put 50 g of Substance A in the beaker labeled A and 50 g of Substance B in the beaker labeled B.
The solution in both beakers was stirred for 1 minute. The amount of substance left undissolved in the beakers was weighed. The experiment was repeated for different temperatures of water and the observations were recorded as shown.

Experimental Observations
Substance	Mass of Undissolved Substance at Different Temperatures (gram)
20 °C	40 °C	60 °C	80 °C
A	50	50	50	50
B	10	8	5	2

Part 1: Which, if any, substance is soluble in water?
Part 2: Explain how the data helped you determine solubility for both substances for temperatures 20 °C to 80 °C

A
  1. Substance B is clearly soluble in water, substance A’s mass did not change when attempted to be dissolved in water.
  2. The data allows you to determine that substance B has a high soluble rate, but like most substances with it the higher the temperature the more it was able to dissolve. Whilst for substance A nothing changed regardless of the temperature it was dissolved at.
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6
Q 
Which of the following steps is usually done right before experimentation in the scientific method of investigation?
Construct a hypothesis
Ask a question
Do background research
Analyze data and draw conclusions
A

Construct a hypothesis

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7
Q

What best describes a material’s ability to dissolve?

A

Solubility

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8
Q

The table shows the mass and melting point of some substances.

Melting Point of Substances
Mass
(kg)	Melting Point of Tin
(°C)	Melting Point of Lead
(°C)
1	W	Y
2	232	327

Part 1: What will be the values of W and Y for 1 kg of each substance?
Part 2: Explain your answer for Part 1.

A

W= 116, Y= 163.5

  1. The mass of each substance given is per 2 kg, so I divided each of the numbers given by 2 in order to find the melting point for each singular kg.
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9
Q

Two descriptions about physical quantities are given below:

Quantity A: It remains constant.
Quantity B: It depends on gravitational pull.

What quantities are these most likely describing?

A

Quantity A is mass and Quantity B is weight.

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10
Q

The properties of a rectangular prism are listed below:

Mass = 120 g
Length = 3 cm
Width = 2 cm
Height = 1 cm

What is the density of the rectangular prism?

A

20 g/cm3

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11
Q

Which of the following is an extensive property?

A

Volume

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12
Q

What is true about a scientific idea?

A

It can be observed and tested

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13
Q

What does weight measure?

A

Force of gravity acting on an object

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14
Q

A 100 kg log of wood was neatly cut into two smaller pieces. What is the total mass of all the smaller pieces put together?

A

100 kg

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15
Q

Polly did an experiment with marbles in a glass bowl to show the movement of particles in solids, liquids, and gases.

A glass bowl is shown with four marbles inside it.

What should Polly do to represent the particles of a solid?

A

Pack the bowl with marbles and then tap it gently.

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16
Q

The image below shows particles flowing by each other.

A square is shown with the title State of Matter. It has three groups of three circles each. Each group is touching the other and are all close to one another.

Which state of matter is most likely represented in the image?

A

Liquid

17
Q

During an investigation, similar glow sticks were placed in two beakers containing water at different temperatures. A record of the investigation is shown below:

Investigation Record
Glow Stick	Beaker Water
Temperature	Duration of Glow Stick in
the Beaker
A	50 °F	2 minutes
B	140 °F	2 minutes

When the glow sticks were bent, chemicals inside reacted to produce a glow. Which statement is most likely correct?

A

Stick B glows brighter as the molecules inside it move faster.

18
Q

All substances taking part in a certain interaction are shown below:

Calcium Carbonate is written after that an equal sign is shown followed by Calcium Oxide followed by an addition sign followed by Carbon dioxide. Just below Calcium Oxide 112 grams is written and just below Carbon dioxide 88 grams is written

Which of the following is the correct estimate of the amount of calcium carbonate used in the interaction?

A

Sum of 112 g and 88 g

19
Q

Which of the following represents a chemical change?

A

Burning of Wood

20
Q

At which of the following temperatures is the speed of a given chemical reaction the fastest?

10
20
30
40

A

40

21
Q

Which of the following most likely happens when thermal energy is removed from a chemical reaction?

A

Fewer Collisions

22
Q

Is mass conserved when 200 g of water undergoes a physical change? Use complete sentences to support your answer by explaining how this can be demonstrated.

A

Mass is conserved when water undergoes a physical change. When a substance goes through a physical change that means the physical appearance of the object has changed but the mass does not. As it demonstrates here. This can be demonstrated by boiling water. If I were to boil 200g of water and it then evaporated, the amount of evaporated water would still be 200g.

23
Q

Which of the following most likely happens during a physical change?

A

Substance changes its form but not its molecular composition.

24
Q

Which of these is true about the possible number of compounds that can be formed?
There is an infinite number of possible compounds because some compounds are not reactive.
There is an infinite number of possible compounds because the number of elements is unlimited.
There is a finite number of possible compounds because the number of elements is limited.
There is a finite number of possible compounds because all compounds are reactive.

A

There is a finite number of possible compounds because the number of elements is limited.

25
Q

Litmus paper strips were dipped in two different unknown liquids. The table below shows the pH of the two liquids:

Litmus Test for Unknown Liquids
Litmus Paper Strip pH of Liquid
X 9
Y 4

A

X will turn blue and Y will turn red.

Above 8.2 will turn blue.
Below 4.5 will turn red.
8.2 is considered a base
Below 7 is an acid

26
Q

Which of the following changes is observed when we move across the row from left to right in the periodic table?

A

Atomic radius decreases

27
Q

Which of the following is created when solids, liquids, or gases mix with one another?

A

Mixture

28
Q

Subatomic Particles

A

Proton, Neutron, Electron

29
Q

What is the name of the group of elements that have properties of both metals and nonmetals?

A

Metalloids

30
Q

Which type of ions are formed when an acid is dissolved in water?

A

Hydrogen ions

31
Q

How to determine the number of protons, neutrons, electrons

A

Potassium has 19 protons, 19 electrons, around 11 neutrons. I was able to determine this because the number of protons/ electrons - atomic mass is the number of my neutrons!
Atomic Mass is the decimal number. The whole number is protons/electrons

32
Q

If they are in the same column, up and down, they have the same property!!

A

If they are in the same column, up and down, they have the same property!!

33
Q

Use complete sentences to differentiate between acids and bases on the basis of taste. Give an example of each type.

A

When differentiating acids and bases between tastes the two solutions are very different. An acid has a sour taste, such as lemon would, a lemon is also an acid. While a base would have a bitter taste. For example, coffee, while coffee itself is not a base, caffeine is. And caffeine is of course in coffee.

34
Q

What is the attraction between atoms when they react called?

A

Chemical Bond

35
Q

Which type of mixture can be separated using distillation?

A

Homogeneous mixture with components of different boiling points

36
Q

Heterogeneous mixtures can be physically separated like m&ms, Homogeneous cannot, they are like oil and water.

A

Heterogeneous mixtures can be physically separated like m&ms, Homogeneous cannot, they are like oil and water.

37
Q

When positively charged particles were radiated onto a gold atom, a few of the particles bounced back. Which of the following caused this?

A

Positively charged protons in the nucleus of the gold atom

Tori - 8th Grade Science (9 decks)

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