4E SciChem TYS MCQ Topics 1 & 2

A student carried out an experiment to study the rate of reaction when a piece of magnesium was added to some dilute hydrochloric acid.

Which piece of apparatus is not required for this experiment?

• conical flask

• stopwatch

• gas syringe

• bunsen burner

Answer explanation

To study the rate of reaction between magnesium and acid, the volume of hydrogen gas produced per unit time is measured.

A conical flask is used to contain the chemicals.

A stopwatch is required to measure the time intervals of the reaction.

A gas syringe is used to collect and measure the volume of hydrogen gas produced at regular time intervals.

A bunsen burner is not needed.

The diagrams show two methods of collecting gases.

Which are the properties of a gas that can be collected by both methods?

• Property 1: insoluble in water

  Property 2:

  denser than air

• Property 1: insoluble in water

  Property 2:

  less dense than air

• Property 1:

  soluble in water

  Property 2:

  denser than air

• Property 1:

  soluble in water

  Property 2:

  less dense than air

Answer explanation

Displacement of water (method 1) is suitable for insoluble gases as soluble gases will dissolve in water.

Upward delivery (method 2) is used for gases less dense than air as they will displace air at the top of the gas jar.

Barium sulfate is insoluble in water.

Barium sulfate is made by adding 20 cm³ of aqueous barium nitrate to dilute sulfuric acid.

Which pieces of apparatus are needed to obtain solid barium sulfate from aqueous barium nitrate and dilute sulfuric acid?

• 1, 2 and 4

• 1, 4 and 5

• 2, 3 and 4

• 2, 4 and 5

Answer explanation

Barium sulfate is insoluble and can be prepared by precipitation reaction.

A measuring cylinder (apparatus 4) is required to measure 20 cm³ of aqueous barium nitrate.

Barium nitrate is added to dilute sulfuric acid in a beaker (apparatus 2) for precipitation reaction to take place.

The precipitate is then filtered using a filter funnel (apparatus 1) lined with filter paper.

Which apparatus is used to collect a gas that is soluble in water and less dense than air?

• 
• 
• 
• 

Answer explanation

Since the gas is soluble in water, any method that involves bubbling the gas through water is not suitable.

Since the gas is less dense than air, it can be collected by the upward delivery method.

Which pieces of apparatus must be used to carry out an experiment to measure the change in temperature when 1 g of magnesium powder is added to excess dilute hydrochloric acid?

1 a balance

2 a gas syringe

3 a stopwatch

4 a thermometer

• 1 and 2

• 1 and 4

• 2 and 3

• 3 and 4

Answer explanation

A balance is used to measure the mass of magnesium powder.

A thermometer is used to measure the temperature of the mixture.

A stopwatch is not needed as we do not need to measure temperature at regular time intervals.

Methanol boils at 65 ^oC and water boils at 100 ^oC.

Methanol and water are completely miscible with each other.

Which method is used to separate a mixture of these two liquids?

• evaporation

• filtration

• fractional distillation

• paper chromatography

Answer explanation

Fractional distillation is used to separate two miscible liquids with different boiling points.

The diagram shows a chromatogram of five different inks.

How many different dyes were used to make the five inks?

• 3

• 4

• 5

• 12

Answer explanation

Spots that have travelled over the same distance from the starting line represent identical dyes.

Since there are 4 different spots, there are 4 different dyes in the five inks.

A coloured ink is compared with four different dyes.

The chromatogram produced is shown in the diagram.

Which dyes does the ink contain?

• 1 and 2

• 1 and 4

• 2 and 3

• 2 and 4

Answer explanation

By comparing the distances travelled by each component, the components of dyes 1 and 4 travel the same distance as the components of the ink.

Which method is used to obtain potassium chloride crystals from an aqueous solution of potassium chloride?

• evaporation

• filtration

• fractional distillation

• paper chromatography

Answer explanation

The method used should be crystallisation (which is not given as one of the options).

Crystallisation involves evaporation of water till the solution becomes saturated.