MEDIUM
Lower Secondary Stage 8
IMPORTANT
Earn 100

The melting point of calcium is 840°C.
The melting point of lithium is 180.5°C.

Explain why the melting points are different.

Important Questions on Elements, Compounds and Mixtures

MEDIUM
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 1>Q 4
Give reason: When chocolate is left in the warm sun, it starts to melt.
EASY
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 2

The two particle diagrams shows the same gas at different pressures.

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State which diagram shows the gas at higher pressure _____.

EASY
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 3
Which statements are true? 
Tick two boxes.
EASY
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 6

Look at the diagram. It shows a sealed gas syringe.
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Describe what will happen to the pressure of the gas as the plunger is pushed in.

 

EASY
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 6

Look at the diagram. It shows a sealed gas syringe.
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Use your knowledge of particle theory to explain the answer.what will happen to the pressure of the gas as the plunger is pushed in. 

MEDIUM
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 7
Pierre was about to go out when he notices that his bicycle has a flat tyre. 
He is looking worried because he does not know how to repair it. 
Describe what happened to the amount of air in the tyre. Suggest a reason for your answer.
EASY
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 8
A perfume was spread at the front of the class. 
The student predicted that the whole class would be able to smell the perfume. 
A minute letter the student sitting near the front could smell The Perfume, but the students at the back could not. Explain this observation.
EASY
Lower Secondary Stage 8
IMPORTANT
Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 2>Q 9

When concentrated hydrochloric acid reacts with concentrated Ammonia solution a white compound is formed. 
A teacher set up of the following demonstration.
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Why was universal indicator included in the demonstration?