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WorksheetsScience Chemistry 8th Grade
Total questions: 30
Worksheet time: 23mins
In carbon dioxide, each oxygen atom shares four electrons with the carbon atom. What is this type of bond called?
double covalent
ionic
Polar Covalent
Trip covalent
Ethanol has six hydrogen atoms, two carbon atoms, and one oxygen atom. Which is the correct chemical formula of the model below?
C26HO
C2H6O
2CH6O
6HCO
In a reaction that has one reactant and two products, the _____.
mass of the products is four times the mass of the reactants
mass of the products is not related to the mass of the reactants
products have twice as much mass as the reactants
mass of the products is equal to the mass of the reactants
Which equation is balanced?
Use the symbols representing types of reactions to answer the following questions.
Which figure models a single-replacement reaction?
IV
II
I
III
Which type of atom forms a flexible bond with other atoms of the same element by sharing a large pool of valence electrons?
Metal
Metalloid
Non-metal
All substances _____.
contain hydrogen
are elements
have a fixed arrangement of atoms
Are compounds
Which type of reaction is the opposite of a synthesis reaction?
decomposition
double-replacement
single-replacement
In a chemical formula, the number of each type of atom in the compound is shown by numbers called ____.
Chemical symbols
Superscripts
oxidation numbers
subscripts
Which activity is a type of combustion reaction?
Formation of table salt
burning wood
breaking down water
Why is the law of conservation of mass true?
All molecules at the start of a chemical reaction are present at the end of the reaction.
All atoms at the start of a chemical reaction are present at the end of the reaction.
All the molecules in a substance remain intact during a chemical reaction.
The substances at the start of a chemical reaction gather more atoms to make up for those lost in the reaction.
In the compound, H2O, the electrons in the bonds are unequally shared between oxygen and hydrogen, forming ____.
Polar bonds
non-polar molecules
ionic bonds
cations
According to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactants?
The mass of products is sometimes greater.
The mass of reactants is greater.
There is no relationship.
The masses are always equal.
Atoms that gain electrons become ions with a _____ charge.
Like
equal
negative
positive
Aspartame is an artificial sweetener; its formula is C13H16N2O5. Which element in the formula has the greatest number of atoms?
Hydrogen
Carbon
Oxygen
nItrogen
Which type of atoms are found in metallic bonds?
Non-matal atoms
Salt atoms
valance atoms
metal atoms
Hydrogen peroxide (a) and forms water and oxygen gas.
The French chemist, (a) , conducted experiments that led to the law of conservation of mass.
Which equation is balanced?
Zinc combines with hydrochloric acid, the zinc replaces hydrogen. The chemical equation for this reaction looks like: Zn + 2HCl → ZnCl2 + H2
This is a _____ reaction
decomposition
single-replacement
synthesis
double-replacement
Sugar is an example of a (a) molecule due to the unequal sharing of electrons.
Aluminum oxide is a chemical formula with two aluminum atoms and three oxygen atoms. Which is the correct chemical formula?
Which situation does NOT occur during chemical reactions?
Atoms are destroyed.
Atoms are destroyed.
Mass is conserved.
Bonds are broken.
An explanation for the law of conservation of matter is that the same (a) is present before and after the reaction.
Which statement is correct?
Physical changes produce new substances; chemical changes do not.
Chemical changes produce new substances; physical changes do not.
Both physical changes and chemical changes produce new substances.
Neither physical changes nor chemical changes produce new substances.
Each substance written to the right of the arrow in a chemical equation is a ____.
product
precipitate
reactant
catalyst
Which of the following bonds is polar?
F-F
O-O
O-H
H-H
Geoff observed an experiment in which one compound underwent a chemical reaction that produced two compounds. He classified this as a (a) reaction.
The number of products is always less than the number of reactants in a _____.
double-replacement reaction
synthesis reaction
decomposition reaction
single-replacement reaction
The _____ determines the mass of the products of a chemical reaction.
amount of energy absorbed or released by the reaction
number of different products and reactants
rate at which the reaction occurs
mass of the reactants
