WorksheetsLaw of conservation of mass
Total questions: 20
Worksheet time: 39mins
Name
Class
Date
1.
Matter can not be created nor destroyed: it can only be
a)
Destroyed a little bit
b)
Invisible
c)
Transformed, changed
d)
None of the above
2.
The number to the lower side of an element is a
a)
Subscript
b)
Superscript
c)
Coefficient
d)
Charge
3.
The number in front of a compound or element is a
a)
Subscript
b)
Coefficient
c)
Superscript
d)
Charge
4.
A chemical reaction is balanced when
a)
both sides have the same elements
b)
Both sides have the same number of atoms
c)
Same subscripts
d)
Same coefficients
5.
Which of these is not a chemical reaction?
a)
Burning of wood
b)
Milk going bad
c)
Mixing vinegar and baking soda
d)
Melting of ice
6.
The coefficient in 3H2O is
a)
6
b)
2
c)
3
d)
5
7.
If reaction starts with 20g of reactants it should produce
a)
a total of 40g of products
b)
a total of 10g of products
c)
a total of 80 g of products
d)
a total of 20g of products
8.
In a reaction A + B ----> C, reactant A has 5g and product C has 9g. How many grams does reactant B should have?
a)
4g
b)
5g
c)
9g
d)
14g
9.
What will weigh more when a chemical change is complete? The reactants before the chemical reaction, or the product after the reaction is complete?
a)
They both will weigh the same
b)
The product always weighs more than the reactant
c)
The reactant will weigh more than the product
d)
They both will loose mass after the reaction
10.
Measure of the amount of matter
a)
mass
b)
volume
c)
weight
d)
density
11.
What is the Law of Conservation of mass?
a)
Mass is created in a chemical reaction
b)
Mass is created in a physical change
c)
New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
d)
Mass is never created or destroyed
12.
Since gasses weigh nothing, when they are produced in a reaction they do not have to be accounted for.
a)
True
b)
False
13.
Which are the reactants in the following reaction?
2Mg + O2 ---> 2MgO
2Mg + O2 ---> 2MgO
a)
Mg and O
b)
MgO
c)
Mg and MgO
d)
O and MgO
14.
How many oxygen atoms are in this chemical formula?
a)
6 oxygen atoms
b)
2 oxygen atoms
c)
3 oxygen atoms
d)
4 oxygen atoms
15.
Bob puts 200 grams of ice into a pitcher with 900 grams of water. He gets distracted and comes back later to find that the ice has melted in the water. How many grams of water does Bob now have in the pitcher?
a)
200 g
b)
700 g
c)
1,100 g
16.
24 g of magnesium reacts with 38 g of fluorine to produce _____ g magnesium fluoride
a)
62
b)
38
c)
24
d)
14
17.
Students react baking soda & vinegar.
Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?
Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?
a)
The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.
b)
Bubbles were produced during the reaction, which meant that a gas was being produced.
c)
The plastic bag did not change in any way, indicating that it was not involved in the reaction.
d)
The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.
18.
When CaCO3 is heated, it forms CaO and CO2. Which of these statements best describes the mass of the products if 100 g of CaCO3 is heated?
a)
The difference in the products’ masses is equal to the mass of the CaCO3
b)
The sum of the products’ masses is less than the mass of the CaCO3
c)
The mass of each product is equal to the mass of the CaCO3
d)
The sum of the products’ masses equals the mass of the CaCO3
19.
Molecule
a)
A group of atoms bonded together
b)
Basic unit of a chemical element
c)
Coefficient
d)
Subscript
20.
Balance this equation-
__P4 + __O2 --> __P2O3
__P4 + __O2 --> __P2O3
a)
it is already balanced
b)
2, 1, 3
c)
1, 2, 3
d)
1, 3, 2
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