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WorksheetsChemistry -- 8th Grade Science Review
Total questions: 40
Worksheet time: 20mins
Which statement best describes evidence that a chemical reaction occurs as a cake bakes?
The water in the cake batter evaporates.
The cake rises as gas bubbles form in the baking cake.
The cake takes the shape of the container in which it is baked;
The water in the cake batter is used to keep the cake moist as it bakes.
Which of the following best describes a physical change?
Wood changes color as it burns.
A solid forms from two liquids.
Bubbles form in boiling water.
A matchstick burning.
How many atoms of Oxygen are in the chemical formula for glucose C6H12O6 ?
6
12
18
24
How many elements are in the chemical formula CH3CO2?
1
3
4
7
A chemical formula shows all of the following except....
the chemical symbols of the element
the number of atoms of each element
the elements found in a compound
the number of protons in a nucleus
What is the term for the number 8 in the following chemical formula 2C8H18 ?
Reactant
Product
Coefficient
Subscript
All of the following are evidence of a chemical reaction except....
Production of a gas
Formation of a precipitate
Change in the shape of the matter
Change in the temperature of the matter
All of the following are examples of a chemical compound except....
MgO
O2
C8H18
HCl
All of the following are examples of elements except...
Cu
Cl
CO
He
What is the appropriate subscript for hydrogen?
1
3
4
7
How many molecules are found in the following chemical formula 3(NH4)2SO4 ?
2
3
4
11
Which of the following is an example of a chemical change involving water?
Salt dissolves in water.
Liquid water freezes to become ice.
Ice changes from a solid to a gas.
Water is broken up to hydrogen and oxygen using electricity.
Which of the following is true?
In chemical changes the mass is greater in the reactants than the products.
Chemical changes always cause a new substance to form.
Chemical changes always involve a change in state of matter.
Chemical changes happen more often than physical changes.
Which of the following is not true when referring to the Law of Conservation of Mass?
The mass of the reactants must be the same as the products.
The elements in the reactants must be the same as the elements in the products.
The amount of atoms in the reactants must be the same as the amount of atoms in the products.
The coefficients in the reactants must be the same as the coefficients in the products.
A chemical change is different than a physical change because in a chemical change...
Chemicals are used.
Molecules do not physically touch.
The change can be seen and a physical change cannot.
A new substance is formed and in a physical change it is not.
In a chemical reaction....
The atoms in the reactants always stay together to form the products.
The atoms of the reactants rearrange and re-bond to form the products.
New atoms are formed which combine to make the products.
Some atoms disappear while others multiply to make the product.
A student mixed baking soda and vinegar and observed foaming and bubbles. The student concluded that ....
the bubbles indicated a chemical change was occurring.
the baking soda and vinegar were products of the reaction.
the gas was oxygen.
only a physical change was occurring.
How many total atoms are in this formula 2C2H4O?
8
9
13
14
Which of the following should be placed in box A?
Subscript
Coefficient
Reactant
Yields
Which of the following is correct?
Product → Reactant
Reactant = Product
Reactant ← Product
Reactant → Product
Which of the following contains the greatest number of elements?
H2O
CH3CO2
NaHCO3
C2H4O2
The chemical formula for Ethanol is shown. How many atoms of each element are in one molecule of Ethanol?
2 carbon atoms, 5 hydrogen atoms, 1 oxygen atom
2 carbon atoms, 6 hydrogen atoms, 1 oxygen atom
4 carbon atoms, 3 hydrogen atoms, 6 oxygen atom
6 carbon atoms, 7 hydrogen atoms, 2 oxygen atom
How many atoms of Aluminum are in 2Al2(CO3)3 ?
1
2
4
5
Does the following equation follow the Law of Conservation of Mass (is it balanced)? N2 + 3H2 → 2NH3
Yes, all elements are the same on both sides.
No, all elements are not the same on both sides.
Yes, all elements have the same amount of atoms on both sides.
No, all elements do not have the same amount of atoms on both sides
Which molecule has twice as many Al atoms as Al2O3?
3Al2O3
2Al2O3
4Al2O3
(Al2O3)) 4
6 CO2 + 6 H2O → C6H12O6 + 6 O2 How many atoms are in the product of this equation?
36
24
14
12
A chemist placed a piece of pink paper in a beaker. He placed the beaker over an open gas flame produced by a Bunsen burner. As the paper was heated, it turned black and produced smoke. Later, the flakes of paper crumbled and became ash. Which of the following observations about the burning paper does not provide evidence of a chemical reaction?
As the paper burned, it released black smoke.
As the paper burned, it transformed into ash.
As the paper burned, its color changed from pink to black.
As the paper burned, it became smaller.
Two chemicals were mixed together and produced bubbles. What kind of change is happening?
Chemical change
Physical change
Phase change
None of the above
How many elements are in the following chemical formula?
Al3
1
2
3
4
How many atoms of Hydrogen are found in the following chemical formula? C2H3O2NH4
3
4
7
12
Is the following equation balanced?
4 FeS + 7 O2 → 2 Fe2O4 + 4 SO2
Yes
No
What part of the atom is responsible for all chemical reactions?
Proton
Neutron
Electron
Valence electron
Which of the following is true about an element and a compound?
An element cannot be broken down into simpler substances, but a compound can.
A compound cannot be broken down into simpler substances, but an element can.
Compounds are found everywhere, while elements are only found in certain places.
Elements are found everywhere, while compounds are only found in certain places.
Which of the following is the best example of a chemical change?
A tree is chopped in to firewood.
A student uses temporary hair dye on Halloween to turn their hair red.
A student left his father's wrench outside and it rusted.
Water was placed in dry ice and froze.
In a balanced equation, the number of atoms in the ______ and _____ must be equal.
Product, Coefficient
Product, Reactant
Subscript, Coefficient
Product, Quotient
When stomach acid helps to break down food into smaller particles, this is an example of what kind of change?
Physical change
Phase change
Chemical change
Atomic change
The group of elements and/or compounds prior to a chemical reaction are known as the
Subscripts
Reactants
Coefficients
Products
Which of the following best describes the Law of Conservation of Mass?
Mass must be conserved for survival
The amount of mass in the Universe is always changing.
Mass needs to be conserved for energy efficiency.
Mass can neither be created nor destroyed.
What is the density of an object that has a mass of 100 g and a volume of 10?
10
100
110
1000
What is the mass of an object that has a density of 20 g/ml and a volume of 10 ml?
10
20
30
200
