Use the clues provided to complete the crossword puzzle. Across Down 2.The element's chemical symbol is Ar 1.This element is commonly found as shoot. 4.The element's chemical symbol is Mg . 3.You can find all the elements listed here. 5.About 21% of Earth's atmosphere. 8.The simplest particle in the particle theory. 6.About 78% of Earth's atmosphere. 11.This element is used to make bridges. 7.Often used to make rings and jewellery. 9.This gas helps clean swimming pools. 10.The element's chemical symbol is Be . 12.This gas can be used to fill party balloons.

Any substance that cannot be decomposed into simpler substances by ordinary chemical processes is called an element. Example: Hydrogen, Oxygen, Carbon etc. Each element is made of the same atoms. The properties of elements include colour, density, melting point, boiling point, and thermal and electrical conductivity.

Mia and Ahmed heated a mixture of iron and sulphur using the equipment below. Why did they add mineral wool to the end of the test tube ?

When a mixture of Iron and Sulphur is heated, the sulphur melts and reacts with the iron exothermically to form iron(II) sulphide. The mineral wool plug in the mouth of the test tube prevents sulphur vapour from escaping and possibly catching fire.

Mia and Ahmed heated a mixture of iron and sulphur using the equipment below. What could they do to reduce the risk in this experiment ?

To reduce the risk in the experiment we can follow some steps: Step 1: We must use a Bunsen burner in adult supervision. Step 2: Since it is a highly exothermic reaction so must wear eyeglasses and gloves while doing the experiment. When Iron reacts with sulphur, it forms a new compound called Iron(II)Sulphide ( FeS ) .

EASY

Lower Secondary Stage 8

IMPORTANT

Earn 100

Crack the code.

Write down the element symbols to find the hidden words.

Element Symbol

Carbon ___

Hydrogen _

Iodine _

Sodium ___

Important Questions on Elements, Compounds and Mixtures

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 3>Q 5

Look at diagram A, B and C.
Question Image
State which diagram represents elements.
Give a reason for your answer.
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MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 3>Q 6

Explain why chemists choose chemical symbols.
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HARD

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 4 - Elements, Compounds and Mixtures>Exercise 3>Q 7

Use the clues provided to complete the crossword puzzle.
Question Image

Across	Down
2.The element's chemical symbol is $Ar$	1.This element is commonly found as shoot.
4.The element's chemical symbol is $Mg$ .	3.You can find all the elements listed here.
5.About 21% of Earth's atmosphere.	8.The simplest particle in the particle theory.
6.About 78% of Earth's atmosphere.	11.This element is used to make bridges.
7.Often used to make rings and jewellery.
9.This gas helps clean swimming pools.
10.The element's chemical symbol is $Be$ .
12.This gas can be used to fill party balloons.