102 terms

DCIS - Science Final 8th Grade Study Guide - Sylvia Riad

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What must a good hypothesis be?
Testable
At the end of an investigation, what could you do if you conclude that your results do not support your hypothesis?
Change the hypothesis, change the procedure, gather more information, or ask new questions
What is the most common cause of accidents in the labratory?
Not reading and following the directions.
What is science?
The knowlegde gained about the natural world by investigation
Whcich is a way science saves lives?
A meteorologist learns to predict tornadoes
What two things should you do after an accident at the laboratory?
Make sure you are safe, and tell your teacher
Which statement is NOT true of scientific methods?
Scientists always follow the steps in the same order
How does the symbol for animal safety look like?
There is a picture someone holding a mouse in there hand.
At the end of an experiment, what must you draw?
A conclusion
Suppose you asked the question, "what kind of ants are in my backyard?". What would be the best way to gather data to investigate your reasearch?
Observe Ants in your yard.
Answering some questions by looking up the the facts in the book is an example of ___?
Reasearch
Which of the following circumstances would result in the rejection of scientific data?
Scientists could not repeat their results
Which of the following is useful for summarizing large amounts of infonnation?
Mathematics
Which of the following is generally true for SI units?
Changing from one unit to the other is easy
What is a summary of many experimental results and observations called?
A law
Which of the following is a limit of models?
Models do not act exactly like the real object
Which of the following is a limitation of scientific models?
They do not act exactly like the real thing
What is an example of a conceptual model?
A model of a galaxy forming
Which of the following usually happens during a chemical change?
Heat is released or absorbed
Which of the following units would be best for describing the volume of vinegar used in an experiment?
Liters or Milliliters
Why is a melting ice cube an example of a physical change?
Becuase the form, not the identity, of the substance changes.
The amount of liquid used in scientific experiments is typically expressed in?
Liters or Milliliters
To compare the densities of oil and water, pour the liquids into a container and observe how they?
Seperate into layers
Why is dens1ty considered a useful property for identifying matter?
Density is unique to each substance
Which statement is NOT true of atoms and molecules
They never bump into each other
Are Particles of gas locked into a position?
Particles of gas are not locked into position.
Which of the following is true about a substance's melting point?
It is the same as a freezing point
What is a direct change from a solid to a gas called?
Sublimation
A graph that shows the change in temperature of a substance as it is heated will show?
A staright line as the substance melts.
What can be said about the properties of a compound?
They are different from the properties of the elements that form a compound
If a spoonful of salt is mixed in a glass of water, what is the water called
A solvent
(not a solution)
What causes an object to start moving?
unbalanced forces
An element contains only one kind of?
Particle
During what type of reaction do the atoms of two or more elements join to form compounds?
Chemical Reaction
What particle did J.J. Thompson discover?
An electron
An atom of Gold with 79 protons, 79 electrons, and 118 neutrons would have a mass number of?
197
What did Bohr, Democritus, Thomson, Dalton and Rutherford all have in common?
They all developed ideas about atoms
The plums in Thompson's plum-pudding model of the atom represent what?
Electrons
If Hydrogen-1 has 1 proton, how many protons does Hydrogen-2 have?
1 proton
What necessary for substances to burn?
Oxygen
Why can metals bend without breaking?
Metals contain constantly moving electrons
What are charged particles that form when atoms gain or lose electrons
Ions
What is a molecule made up of two atoms called?
A diatomic molecule
What type of bond is formed by the attraction between positively charged metal ions and the electrons around them?
A metallic bond
What ending is used for the names of negative ions formed when atoms gained electrons?
-ide
What is the most important factor in determining how an atom will bond?
The number of electons in the outmost energy level.
What is NOT a property of metals associated with metallic bonds?
Brittleness
What is the charge of an ionic compound?
0 (zero)
How many oxygen atoms are present on the reactant side of the chemical equation
4FE + 3Osubscript2 --->2Fe subscript 2 O subscript 3
6
Name a sign of a chemical reaction?
Solid precipitate
How many atoms are represented in the formula
CaCo subscipt 3?
5
The law of conservation of energy states that energy cannot be created or __?
destroyed
Name a covalent compound.
dinitrogen dioxide
When all molecules of an acid break apart in water, the solution is called a ?
Strong Acid
What type of bond holds atoms or ions together?
Chemical Bond
What causes a object to buoy up?
Buoyant Forces greater than the objects weight.
Why can ionic compounds in solution conduct electric current?
becuase the ions are charged and can move freely
Which of the following is NOT a way acids are used?
To make Soap (Soap is a base)
Brittleness and a high melting point are two properties of ?
Ionic Compounds
If almost all the molecules of an acid break apart when it is dissolved in water, the acid is?
Strong
Which of the follwing is NOT used in measuring pH?
a. litmus paper c. a pH meter
b. the pH scale d. a crystal lattice
A Crystal Lattice
Where would orange juice fall on the pH scale?
below 7
What substance is an ionic compound?
Sodium Cholride
Since you know that most calcium hydroxide molecules break apart in water, decide which number on a pH
scale would best describe the water that cement-laying tools were washed in?
10
What makes up proteins?
Amino Acids
What are the subunits that make up nucleic acids?
Nucleotides
What are proteins made of?
Amino Acids
How much of the Human Body is water?
about 70%
Hemoglobin, which carries oxygen in the blood is a - ?
Protein
Over 90% of all known compounds are -?
Organic Compounds
How many atoms can a carbon atom make bonds with?
4
Which of the following are the two factors used to calculate average speed?
Total Distance and Time
When can friction be harmful?
A rough wood scratching you skin
How can you reduce friction?
Place ball bearings between wheels and bicycles
Once an object starts moving, static friction is replaced
by ?
Kinetic Friction
What force affects all matter, including all objects in the Solar System, based on mass?
Gravity
Why does a crumpled piece of paper land on the ground before a flat sheet of paper?
There is more air resistance on the flat paper
Why does a ball thrown level to the ground move downward?
Gravity pulls the ball toward the ground.
What happens to the weight and mass of an object when the object is moved from Earth to Jupiter?
weight increases, mass remains the same
What is not an example of projectile motion?
The path of a crate sliding along flat group
What has the most acceleration?
An empty shopping cart pushed with a hard force.
Water Pressure ___ depth.
increases with depth
How does atmospheric pressure change as you go from the top of a mountain to sea level?
The pressure decreases
What happens when the muscle in your chest moves to cause you to exhale?
The space in your chest decreases
The color of a star depends on its __.
Temperature
What can scientists learn about a star from a spectrum?
Its composition and temperature
Why do all the stars appear to make one complete circle around Polaris every 24 hours?
Becuase of the Earth's pole pointing at Polaris and the Earth's rotation
The H-R diagram shows the relationship of a stars surface and its __.
Absolute Magnitude
Radiation left over from the big bang is called
Cosmic Background Radiation
What is a collection of billions of stars, dust, and gas held together by gravity?
A Galaxy
According to the big bang theory, how did the universe begin?
With a big explosion
About 14 billion years ago, all matter and energy in the universe was compressed into an extremely small volume that exploded and began expanding in all directions, according to the_____.
Big Bang Theory
Stars are born in large clouds of gas and dust in interstellar space called___.
Nebulas
After the solar nebula collapsed, its center became very hot, and.
Planetesimals dormed in the disk
Why is the planet Uranus considered a gas giant?
It has a deep, massive, atmosphere
What causes the phases of the moon?
The relative positions of the Earth, Moon, and Sun.
A spherical cloud of gas and dust that surrounds a comet's nucleus is called a(n)__.
Coma
Which of the following is a body that reaches Earth's Surface?
A Meteorite
One way that sciecntists measure distances in space is by using __.
Astronomical Units
Scientists measure distances within the Solar System using ____.
The Speed of Light
Helium is/is not a common element of the human body.
is not
Mass is _____?
The measure of the amount of matter
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