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This exam was created by a large language model. Please use it with caution, as inaccuracies may be present. Always verify critical information.

What is the best definition of matter?

Select one option

anything that has mass and takes up space

anything that can be seen

a form of energy

a type of force

Which of the following are the four common states of matter?

Select one option

hot, cold, warm, cool

solid, liquid, gas, plasma

proton, neutron, electron, nucleus

melting, freezing, boiling, condensing

Where are protons located within an atom?

Select one option

electron cloud

nucleus

orbitals

outside the atom

What is the electrical charge of an electron?

Select one option

positive

negative

neutral

variable

What characteristic primarily determines an element's identity?

Select one option

the number of neutrons

the number of electrons

the number of protons

its atomic mass

Which of the following is typically a sign that a chemical reaction has occurred?

Select one option

change in shape

change in state (e.g., melting)

dissolving in water

formation of a gas (bubbles)

In a chemical equation, where are the reactants typically located?

Select one option

right side

left side

above the arrow

below the arrow

What is a force?

Select one option

a type of energy

a push or a pull

the amount of matter in an object

the speed of an object

Which force is responsible for objects falling to the Earth?

Select one option

friction

tension

gravity

normal force

10.

Speed is defined as:

Select one option

the rate at which an object changes its position

the distance traveled per unit of time

the change in velocity over time

the amount of force applied

11.

What are the standard SI units for acceleration?

Select one option

m/s

km/h

m/s $^2$

12.

A car travels a distance of 100 meters in 20 seconds. What is its average speed?

Select one option

2000 m/s

5 m/s

0.2 m/s

80 m/s

13.

The Law of Conservation of Energy states that:

Select one option

Energy can be created but not destroyed.

Energy can be destroyed but not created.

Energy can only be transferred as heat.

Energy cannot be created or destroyed, only transformed.

14.

Which of the following is an example of potential energy?

Select one option

A car moving down a road

A stretched rubber band

A light bulb glowing

A person running

15.

What energy transformation occurs when a light bulb is turned on?

Select one option

Chemical energy to light energy

Mechanical energy to electrical energy

Electrical energy to light and heat energy

Heat energy to electrical energy

16.

Which of the following is an intensive property of matter?

Select one option

Mass

Volume

Length

Density

17.

When balancing a chemical equation, what must be true about the atoms?

Select one option

The number of molecules must be the same on both sides.

The mass of the reactants must be greater than the products.

The number of atoms of each element must be the same on both sides.

The state of matter of all substances must be the same.

18.

A rock has a mass of $150\text{ grams}$ and a volume of $50\text{ cubic centimeters}$ . Calculate its density. Show your work.

19.

A runner completes a $120\text{ meter}$ race in $15\text{ seconds}$ . What is the runner's average speed? Show your work.

20.

How much force is required to accelerate a $10\text{ kg}$ object at a rate of $2\text{ m/s}^2$ ? Show your work. (Use Newton's Second Law: $F=ma$ )

21.

Explain the difference between a physical change and a chemical change in matter. Provide one example for each.

22.

Describe the three main ways that heat energy can be transferred, and give a brief example of each.

23.

Differentiate between speed and velocity. Provide an example to illustrate the difference.

Diagram of an Atom

24.

Which letter represents a proton?

Select one option

25.

Which letter represents the electron cloud?

Select one option

26.

Which subatomic particle (represented by a letter) determines the atomic number of an element?

27.

When water ( $H_2O$ ) is broken down into hydrogen gas ( $H_2$ ) and oxygen gas ( $O_2$ ) through electrolysis, what type of chemical reaction is occurring?

Select one option

Synthesis

Decomposition

Single Displacement

Double Displacement

28.

Iron ( $Fe$ ) reacts with oxygen ( $O_2$ ) in the air to form rust (iron oxide, $Fe_2O_3$ ). What type of chemical reaction is this?

Select one option

Synthesis

Decomposition

Combustion

Acid-Base

Force Diagram

BOX

30 N

20 N

29.

Calculate the net force acting on the box.

30.

In which direction will the box accelerate?

Select one option

To the left

To the right

Upwards

Downwards

Plant Growth Experiment Scenario

A group of 8th-grade science students wants to investigate how different types of fertilizer affect plant growth. They set up an experiment with three groups of identical plants (tomato seedlings).

Group 1: Receives Fertilizer A, dissolved in water. Group 2: Receives Fertilizer B, dissolved in water. Group 3: Receives only plain water (no fertilizer).

All plants are given the same amount of liquid daily, are exposed to the same amount of sunlight, and are kept at the same temperature. They measure the height of each plant weekly for four weeks.

31.

Identify the independent variable in this experiment.

32.

Formulate a testable hypothesis for this experiment.

33.

List at least three important controlled variables that the students must keep constant to ensure a fair test.

34.

Suggest one safety precaution that should be taken during this experiment and explain why it is important.