Chemistry Mid Unit Test

Question 1

What change would be most difficult to reverse

Answer 1

Iron gate rusting

Question 2

As a part of a science lab project Simon was required to perform the following tasks

Heat wax until it melted
Dissolve in salt water
Burn a wooden splint
Make water from a combination of gases

Answer 2

Burn a wooden splint

Make water from a combination of gases

Question 3

Water is decomposed into two products
This illustration by a simple chemical equation shown below

2H2O ~ 2H2 + O2

Answer 3

Formation of gases

Question 4

Friends enjoy the flickering flames Matt was quick to point out that the burning logs which chemical change

He based his observations on

Answer 4

Release of heat

Odour

Formation of smoke

Question 5

The piece of chalk board is crushed into the powder.

It is then mixed with hydrochloric acid and then the chalk disappears as bubbles

Answer 5

Physical 🧽🚿

Then

Chemical 🧪

Question 6

The term precipitate is often associated with chemical change

Answer 6

Formation of a solid