EASE 3 past papers

choose which salt is SOLUBLE in water!

• Lead(II) chloride

• Barium sulfate

• Ammonium chloride

• Calcium sulfate

Answer explanation

All nitrates (NO₃^-) are soluble

Most chlorides (Cl^-) and Most sulfates (SO₄^2-) are soluble, exception AgCl, PbCl₂, PbSO₄, BaSO₄, CaSO₄

Most carbonates (CO₃^2-) are insoluble, except those of Group I elements (alkali metals) and ammonium (NH4⁺).

alkali metals (Na, K) and ammonium (NH4⁺) salts are all soluble

Most of bases (Metal oxide) are insoluble except Na, K and NH4

These base are soluble in water producing alkali solution

soluble base :Na₂O(s) + H₂O(l) → 2NaOH(aq)

solid NaOH in water

NaOH(s) + H₂O(l) → NaOH(aq)

Calcium oxide (CaO), also known as quicklime, is sparingly soluble in water. When calcium oxide is added to water, it reacts vigorously to form calcium hydroxide (Ca(OH)₂), a strong base, and releases heat in the process. The reaction can be represented by the following equation:

CaO(s) + H2O(l) → Ca(OH)₂(aq)

Aqueous ammonium sulfate is made by reacting aqueous ammonia with dilute sulfuric acid.

How is solid ammonium sulfate obtained from the resulting solution?

• crystallisation

• distillation

• filtration

• solvent extraction

Answer explanation

during preparation soluble salt we will get salt solution

and to get the solid salt the last step is to crystalise those solution

Which of the following is insoluble salt?

• silver chloride

• potassium chloride

• zinc chloride

• ammonium chloride

Answer explanation

All nitrates (NO₃^-) are soluble

Most chlorides (Cl^-) and Most sulfates (SO₄^2-) are soluble, exception AgCl, PbCl₂, PbSO₄, BaSO₄, CaSO₄

Most carbonates (CO₃^2-) are insoluble, except those of Group I elements (alkali metals) and ammonium (NH4⁺).

alkali metals (Na, K) and ammonium (NH4⁺) salts are all soluble

Most of bases (Metal oxide) are insoluble except Na, K and NH4

These base are soluble in water producing alkali solution

soluble base :Na₂O(s) + H₂O(l) → 2NaOH(aq)

solid NaOH in water

NaOH(s) + H₂O(l) → NaOH(aq)

Calcium oxide (CaO), also known as quicklime, is sparingly soluble in water. When calcium oxide is added to water, it reacts vigorously to form calcium hydroxide (Ca(OH)₂), a strong base, and releases heat in the process. The reaction can be represented by the following equation:

CaO(s) + H2O(l) → Ca(OH)₂(aq)

Four stages in the preparation of a salt from an acid and a solid metal oxide are listed.

1. Add excess solid

2. Evaporate half the solution and leave to cool

3. Filter to remove unwanted solid

4. Heat the acid

In which order should the stages be carried out?

• 1 - 3 - 4 - 2

• 2 - 1 - 3 - 4

• 4 - 1 - 3 - 2

• 4 - 2- 1 - 3

Answer explanation

Stage 1: An excess of the solid is added to the acid and allowed to react. Using an excess of the solid makes sure that all the acid is used up. If it is not used up at this stage, the acid would become more concentrated when the water is evaporated later (stage 3). (heating the acid before adding the solid can also be done to make the reaction going faster)

Stage 2: The excess solid is filtered out.

Stage 3: The filtrate is gently evaporated to concentrate the salt solution. This can be done on a heated water-bath•

Stage 4: When crystals can be seen forming (crystallisation point), heating is stopped and the solution is left to crystallise.

Stage 5: The concentrated solution is cooled to let the crystals form. The crystals are filtered off and washed with a little distilled water. Then the crystals are dried carefully

A salt is produced in each of the following reactions.

P magnesium + dilute hydrochloric acid        

Q zinc oxide + dilute sulfuric acid        

R sodium hydroxide + dilute hydrochloric acid        

S copper carbonate + dilute sulfuric acid

Which statements about the products of the reactions are correct?

1. A flammable gas is produced in reaction P.

2. Water is formed in all reactions.

3. All the salts formed are soluble in water.

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Answer explanation

Reaction P produce H₂ (flammable gas)

Reaction P only produce salt and H₂, no water

all reaction produce soluble salt

Yono wants to prepare a KCl in the lab.

However He is afraid that KOH and HCl solutions are too dangerous to be mixed in a reaction.

What method should Yono use to prepare KCl safely?

• Directly pouring and mix excess amount of KOH and HCl solutions at the same jar

• Pouring KOH solutions on top of HCl solution little by little without contro

• By titrating HCl solution with KOH solution using buret

• There is no appropriate method to prepare KCl

Answer explanation

for preparing soluble salt of very reactive metal we can use the soluble base of the metal (alkali) and doing titration with acid

Which statement about the Periodic Table is correct?

• Elements in the same group have the same number of electron shells.

• Elements are arranged in order of increasing proton number.

• Metals are on the right and non-metals are on the left.

• The most reactive elements are at the bottom of every group

Answer explanation

Elements are arranged in order of increasing proton (atomic) number.

The properties of the element titanium, Ti, can be predicted from its position in the Periodic Table. Which row identifies the properties of titanium?

• A

• B

• C

• D

Answer explanation

Titanium will have property of those transition metal

they are hard and strong

they have high density

they have high melting and boiling points many of their compounds are coloured

the transition metals, or their compounds, often act as catalysts.

they often show more than one valency

Which is a typical property of transition elements?

• can act as catalysts

• poor electrical conductivity

• low melting point

• low density

Answer explanation

they are hard and strong

they have high density

they have high melting and boiling points many of their compounds are coloured

the transition metals, or their compounds, often act as catalysts.

they often show more than one valency

In the following reaction, aluminium replaces iron from iron oxide to form iron metal and aluminium oxide. This is a redox reaction.

Which pair of substances reacts in a similar way?

• Fe and MgO

• Fe and ZnO

• Mg and CuO

• Zn and MgO

Answer explanation

more reactive metal can displace less reactive metal from its salt or from its oxide

Aluminium can displace iron from iron oxide as Magnesium can displace copper from copper oxide