WorksheetsGrade 7 _ Science Month Chemistry
Total questions: 10
Worksheet time: 20mins
Name
Class
Date
1.
A student dissolves salt in water and leaves the solution under the sun. After some time, the water evaporates and salt crystals remain. What does this show about the nature of the solution?
a)
The solution is a compound.
b)
The solution is a mixture.
c)
The solution formed a new substance.
d)
The salt was destroyed by the sun.
2.
Which of the following statements best distinguishes a compound from a mixture?
a)
A compound can be separated by physical methods.
b)
A mixture can be separated by chemical reactions.
c)
The elements in a compound are chemically combined in a fixed ratio.
d)
The substances in a compound retain their original properties.
3.
A sample of air contains nitrogen, oxygen, carbon dioxide, and water vapor. What kind of matter is air?
a)
Compound
b)
Element
c)
Mixture
d)
Solution
4.
When iron reacts with sulfur and forms a new solid substance that cannot be separated by magnet, the product is most likely a:
a)
Mixture of iron and sulfur
b)
Compound called iron sulfide
c)
Solution of sulfur
d)
Suspension of metal
5.
Two clear liquids are mixed, and after some time, a white solid forms and settles at the bottom. What does this observation suggest?
a)
The liquids form a mixture.
b)
A physical change occurred.
c)
A chemical reaction produced a new substance.
d)
The liquids evaporated completely.
6.
Which of the following statements best explains why carbon dioxide (CO₂) is a compound and oxygen (O₂) is an element?
a)
CO₂ is made of different atoms chemically bonded, while O₂ has identical atoms.
b)
CO₂ and O₂ have two atoms, so both are compounds.
c)
Oxygen O₂ is lighter than carbon dioxide CO₂
d)
Carbon dioxide CO₂ can be separated by filtration.
7.
When magnesium reacts with oxygen, a bright white flame appears and a white powder forms. What evidence indicates a chemical change?
a)
Change in color only
b)
Change in physical state
c)
Formation of a new substance
d)
Evaporation of a liquid
8.
A student describes a substance as colorless, tasteless, and boils at 100°C. Which property is being described?
a)
Chemical property
b)
Physical property
c)
Intensive property
d)
Extensive property
9.
Which statement correctly compares an element and a compound?
a)
Both can be separated by physical means.
b)
Elements contain two or more atoms chemically bonded.
c)
Compounds have different properties from the elements they are made of.
d)
Elements and compounds always exist as mixtures.
10.
Which separation technique would you use to separate sand from water?
a)
a. Distillation
b)
b. Filtration
c)
c. Chromatography
d)
d. Evaporation of solvent
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