Homework Practice

Printable assignment

Physical and Chemical Changes: Spot the Evidence

Physical or Chemical?

Question 1mcq

Which observation is the strongest sign that a chemical change has occurred?

A.A new substance with new properties is formed.

B.Only the size becomes smaller.

C.The object is moved to another table.

D.The same substance is folded into a new shape.

Question 2mcq

Which is mostly a physical change?

A.Burning of paper

B.Melting of ice

C.Rusting of iron

D.Cooking of rice

Question 3mcq

When vinegar and baking soda are mixed, bubbles of gas are produced. This is evidence of:

A.Only a change in shape

B.Only melting

C.Chemical change

D.No change at all

Question 4mcq

Rusting of iron mainly needs iron, oxygen and:

A.Sunlight only

B.Wool fibres

C.Cooking oil as a reactant

D.Water or moisture

Question 5mcq

Cutting a sheet of paper into small pieces is usually classified as a physical change because:

A.no new substance is formed

B.paper changes into ash

C.a gas is produced

D.iron oxide is formed

Rusting and Observations

Question 6mcq

Which change affects state but not the chemical nature of the substance?

A.Milk turning into curd

B.Water freezing into ice

C.A candle wick burning

D.Iron forming rust

Question 7mcq

Which observation during an activity would best suggest a new substance has formed?

A.A pencil is sharpened.

B.A rubber band is stretched.

C.A colour change and gas formation occur after two solutions are mixed.

D.Water is poured from one glass to another.

Question 8mcq

Why does painting an iron gate help prevent rusting?

A.It changes iron into plastic.

B.It adds more water to iron.

C.It makes rust colour invisible only.

D.It keeps oxygen and moisture away from the iron surface.

Question 9mcq

A student says, “All reversible changes are physical and all irreversible changes are chemical.” Which response is best?

A.This is not always true; classification depends mainly on new substance formation.

B.This is always correct.

C.Reversibility is the only test needed.

D.Chemical changes never form new substances.

Question 10mcq

Dissolving sugar in water is usually treated as a physical change because:

A.sugar changes into salt

B.sugar can be recovered by evaporating the water

C.oxygen gas is formed

D.the solution becomes rust