IGCSE 0620 Oct/Nov 2020

Which gas has the slowest rate of diffusion?

• H₂

• NH₃

• CH₄

• CO₂

A chromatography experiment is carried out to analyse the pigments present in four different types of leaf. The student carrying out the experiment forgot to complete his table of results, which is shown.

• A

• B

• C

• D

Which statement about isotopes is correct?

• They have different proton numbers.

• They have different chemical properties.

• They have the same nucleon number.

• They have the same number of electrons in their outer shell.

In the chromatography experiment shown, which label represents the solvent front?

• A

• B

• C

• D

Different methods of separation rely on substances having different properties. Which property does distillation make use of?

• Boiling point

• colour

• particle size

• sollubility in different solvents.

The arrangements of the electrons in two ions formed from elements X and Y are shown. Which equation represents the reaction between elements X and Y?

• X₂ + 2Y --> 2X⁺ + 2Y^–

• X₂ + 2Y --> 2X^– + 2Y⁺

• 2X + Y₂ --> 2X⁺ + 2Y^–

• 2X + Y₂ --> 2X^– + 2Y⁺

Which row identifies compounds that contain single covalent bonds only, double covalent bonds only or both single and double covalent bonds?

• A

• B

• C

• D

Ethyl methanoate, HCOOC₂H₅, burns in excess oxygen to produce carbon dioxide and water. The equation is shown. What is the value of x?

• 2

• 7

• 9

• 18

Rubidium is in Group I of the Periodic Table and bromine is in Group VII. Rubidium reacts with bromine to form an ionic compound. Which row shows the electron change taking place for rubidium and the correct formula of the rubidium ion?

• A

• B

• C

• D

Which statement explains why graphite is used as a lubricant?

• All bonds between the atoms are weak.

• It conducts electricity.

• It has a low melting point.

• Layers in the structure can slide over each other.