PSLE Science Chemistry Topics 2

Question 1

Which method is best for separating salt from a saltwater solution?

Accepted Answer

Evaporation

Answer

Evaporation removes the water, leaving the dissolved salt behind as solid crystals — the same method used in salt pans.

Question 2

What is a solution?

Accepted Answer

A uniform mixture where one substance dissolves completely in another

Answer

A solution is a homogeneous (uniform) mixture where the solute dissolves completely in the solvent and cannot be seen.

Question 3

Which separation method would you use to remove sand from a sand-and-water mixture?

Accepted Answer

Filtration

Answer

Filtration passes the mixture through filter paper, which traps the insoluble sand while allowing water to flow through.

Question 4

Which mixture can be separated effectively using a magnet?

Accepted Answer

Iron filings and sand

Answer

Iron filings are magnetic and are attracted to a magnet, allowing them to be pulled away from the non-magnetic sand.

Question 5

In a saltwater solution, what is the solvent?

Accepted Answer

Water

Answer

Water is the solvent because it is the substance in which the salt (solute) dissolves to form the solution.

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