3.1 Assessment answer
Guide
Q1 :
A chemical reaction is a change in which atoms are rearranged to create new
substances, the atoms are joined together in one way before the reaction and
different way after the reaction.
All chemical reactions :
- Make new substance .
- Transfer energy to or from the surrounding.
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Q2 :
Most chemical reactions are not easily reversible because at the end of the reaction
it is very difficult to get back the substances you started with .
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Q.3
- You can see huge flames or tiny sparks
- Notice a sweet or stinky smell .
- Feel the chemicals are getting hotter or colder .
-Hear a loud bang or gentle fizzing .
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Q.4
- Medicine , like Paracetamol
- Fabrics , like polyster
- Building materials like cement
1
,Q5 .
- Rusting is a chemical reaction that can damage cars , boats or bridges .
- Chemical reactions can make food rot .
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Q6
Atoms
Always
Are not
Always
State - are
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Q7
- Chemical
- Physical
- Physical
- Chemical
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Q8
Chemical changes make new substances. Physical changes do not make new
substances.
Chemical changes are not reversible. Physical changes are reversible.
Chemical changes include burning reactions. Physical changes include changes of
state, dissolving, and mixing.
2
, Q9
Substances
Reversible
Fizzing
Hotter
3
Guide
Q1 :
A chemical reaction is a change in which atoms are rearranged to create new
substances, the atoms are joined together in one way before the reaction and
different way after the reaction.
All chemical reactions :
- Make new substance .
- Transfer energy to or from the surrounding.
----------------------------------------------------------------------------------------------------
Q2 :
Most chemical reactions are not easily reversible because at the end of the reaction
it is very difficult to get back the substances you started with .
----------------------------------------------------------------------------------------------------
Q.3
- You can see huge flames or tiny sparks
- Notice a sweet or stinky smell .
- Feel the chemicals are getting hotter or colder .
-Hear a loud bang or gentle fizzing .
----------------------------------------------------------------------------------------------------
Q.4
- Medicine , like Paracetamol
- Fabrics , like polyster
- Building materials like cement
1
,Q5 .
- Rusting is a chemical reaction that can damage cars , boats or bridges .
- Chemical reactions can make food rot .
---------------------------------------------------------------------------------------------------
Q6
Atoms
Always
Are not
Always
State - are
---------------------------------------------------------------------------------------------------
Q7
- Chemical
- Physical
- Physical
- Chemical
---------------------------------------------------------------------------------------------------
Q8
Chemical changes make new substances. Physical changes do not make new
substances.
Chemical changes are not reversible. Physical changes are reversible.
Chemical changes include burning reactions. Physical changes include changes of
state, dissolving, and mixing.
2
, Q9
Substances
Reversible
Fizzing
Hotter
3
