Simple molecules and covalent bonds — Paper 2 · IGCSE Science - Combined 0653

14 Which diagram represents molecules of hydrogen gas? A B C D

1 marks

Answer: B

This question in 0653/22 Feb/March 2017

16 Which dot-and-cross diagram represents the arrangement of outer-shell electrons in a molecule of nitrogen? A B N N N N C D N N N N

1 marks

Answer: D

This question in 0653/23 May/June 2017

14 The formulae of three substances are shown. substance formula methane CH4 water H2O oxygen O2 Which statement is correct? A Methane is made from five different types of atom. B Methane, water and oxygen are molecules. C Only methane and water are molecules. D Oxygen is made from two different types of atom.

1 marks

Answer: B

This question in 0653/21 Oct/Nov 2017

17 Element Q and element R combine to form a covalent compound, Q2R. The arrangement of the outer-shell electrons in the compound is shown. Q R Q Which compound has the same arrangement of outer shell electrons as Q2R? A carbon dioxide B hydrogen chloride C methane D water

1 marks

Answer: A

This question in 0653/21 Oct/Nov 2017

14 The formulae of three substances are shown. substance formula methane CH4 water H2O oxygen O2 Which statement is correct? A Methane is made from five different types of atom. B Methane, water and oxygen are molecules. C Only methane and water are molecules. D Oxygen is made from two different types of atom.

1 marks

Answer: B

This question in 0653/22 Oct/Nov 2017

14 The formulae of three substances are shown. substance formula methane CH4 water H2O oxygen O2 Which statement is correct? A Methane is made from five different types of atom. B Methane, water and oxygen are molecules. C Only methane and water are molecules. D Oxygen is made from two different types of atom.

1 marks

Answer: B

This question in 0653/23 Oct/Nov 2017

17 Which dot-and-cross diagrams show the outer-shell electrons in molecules of water and of carbon dioxide? water carbon dioxide A H O H O C O B H O H O C O C H O H O C O D H O H O C O

1 marks

Answer: C

This question in 0653/23 Oct/Nov 2017

14 Which statement about atoms and molecules is correct? A Atoms gain or lose electrons to become molecules. B Atoms of the same element contain the same number of molecules. C Molecules are the simplest unit of an atom. D Molecules contain atoms which are covalently bonded.

1 marks

Answer: D

This question in 0653/22 Feb/March 2018

17 Which substance contains a multiple covalent bond? A hydrogen B methane C nitrogen D water

1 marks

Answer: C

This question in 0653/22 Feb/March 2018

14 The diagrams represent different substances. P Q R S T Which row describes the substances? only separate mixture of atoms only molecules atoms and molecules A P Q S B Q T R C T P R D T Q P

1 marks

Answer: A

This question in 0653/21 May/June 2018

14 The diagrams represent different substances. P Q R S T Which row describes the substances? only separate mixture of atoms only molecules atoms and molecules A P Q S B Q T R C T P R D T Q P

1 marks

Answer: A

This question in 0653/22 May/June 2018

14 The diagrams represent different substances. P Q R S T Which row describes the substances? only separate mixture of atoms only molecules atoms and molecules A P Q S B Q T R C T P R D T Q P

1 marks

Answer: A

This question in 0653/23 May/June 2018

14 Sucrose is a covalent compound. It is a solid at room temperature. Which statement about sucrose is correct? A It is made of atoms that are close together and in continuous random motion. B It is made of atoms that are far apart and vibrating about a fixed point. C It is made of molecules that are close together and vibrating about a fixed point. D It is made of molecules that are far apart and in continuous random motion.

1 marks

Answer: C

This question in 0653/22 Oct/Nov 2018

16 Which molecule contains a double covalent bond? A ethene B methane C nitrogen D water

1 marks

Answer: A

This question in 0653/22 Oct/Nov 2018

14 Sucrose is a covalent compound. It is a solid at room temperature. Which statement about sucrose is correct? A It is made of atoms that are close together and in continuous random motion. B It is made of atoms that are far apart and vibrating about a fixed point. C It is made of molecules that are close together and vibrating about a fixed point. D It is made of molecules that are far apart and in continuous random motion.

1 marks

Answer: C

This question in 0653/23 Oct/Nov 2018

16 Which statement about the compound formed between a metal and a non-metal is correct? A It forms strong bonds by sharing electrons. B It has strong bonds between its atoms. C It has strong bonds between metal ions and delocalised electrons. D It has strong bonds between oppositely charged ions.

1 marks

Answer: D

This question in 0653/22 Feb/March 2019

24 Which statement about water is not correct? A A water molecule consists of three atoms covalently bonded together. B The water supply is treated with chlorine to kill the bacteria in it. C Water changes the colour of cobalt chloride paper from blue to pink. D Water has a low melting point because covalent bonds are weak.

1 marks

Answer: D

This question in 0653/21 May/June 2019

14 A molecule of hydrogen has the formula H2. A molecule of a protein contains several different elements. Which statement about these molecules is correct? A They both contain cations and anions bonded together. B They both contain different types of atom. C They both contain more than one atom bonded together. D They both contain only one type of atom.

1 marks

Answer: C

This question in 0653/22 May/June 2019

24 Which statement about water is not correct? A A water molecule consists of three atoms covalently bonded together. B The water supply is treated with chlorine to kill the bacteria in it. C Water changes the colour of cobalt chloride paper from blue to pink. D Water has a low melting point because covalent bonds are weak.

1 marks

Answer: D

This question in 0653/22 May/June 2019

16 Which statement explains why sodium chloride has a much higher melting point than carbon dioxide? A Ionic bonding is weaker than covalent bonding. B Ionic bonding is stronger than covalent bonding. C The attractive forces between ions are stronger than the attractive forces between molecules. D The attractive forces between ions are weaker than the attractive forces between molecules.

1 marks

Answer: C

This question in 0653/23 May/June 2019

18 Which diagram represents a molecule of methanol? A B H H H C O H H C O H H H C D H H H C O H H C O H H H

1 marks

Answer: D

This question in 0653/22 Feb/March 2020

16 Potassium chloride is a solid. Hydrogen chloride is a gas. Which statement explains why potassium chloride has a much higher boiling point than hydrogen chloride? A Covalent bonding is stronger than ionic bonding. B Covalent bonds are stronger than the attractive forces between molecules. C Ionic bonding is stronger than covalent bonding. D Ionic bonds are stronger than the attractive forces between molecules.

1 marks

Answer: D

This question in 0653/22 Feb/March 2021

16 Which row about elements and compounds is correct? elements compounds A are metals only contain ionic or covalent bonds B are non-metals only contain covalent bonds only C are metals or non-metals contain ionic bonds only D are metals or non-metals contain ionic or covalent bonds

1 marks

Answer: D

This question in 0653/21 May/June 2021

15 Which statement explains why ionic compounds have higher melting points than covalent compounds? A Attractive forces are stronger between ions than between molecules. B Ionic bonds are stronger than covalent bonds. C Ions are formed by the transfer of electrons from one atom to another. D The atoms in covalent molecules share electrons.

1 marks

Answer: A

This question in 0653/21 Oct/Nov 2021

14 Which dot-and-cross diagram represents the bonding in a molecule of carbon dioxide? A B C D O C O O C O O C O O C O

1 marks

Answer: C

This question in 0653/22 Oct/Nov 2021

14 How many electrons are shared by the atoms in a nitrogen molecule, N2? A 2 B 4 C 6 D 8

1 marks

Answer: C

This question in 0653/23 Oct/Nov 2021

17 Which dot-and-cross diagram represents the bonding in nitrogen? A B C D N N N N N N N N

1 marks

Answer: B

This question in 0653/22 Feb/March 2022

15 Which statement explains the difference in boiling point between ionic and covalent compounds? A The boiling point of covalent compounds is higher because covalent bonds are stronger than ionic bonds. B The boiling point of covalent compounds is higher because the attractive forces between covalent molecules are stronger than the attractive forces between ions. C The boiling point of ionic compounds is higher because the attractive forces between ions are stronger than covalent bonds. D The boiling point of ionic compounds is higher because the attractive forces between ions are stronger than the attractive forces between covalent molecules.

1 marks

Answer: D

This question in 0653/21 Oct/Nov 2022

15 Which row describes and explains the difference in melting points between ionic and covalent compounds? melting point reason A ionic compounds have ionic bonds are stronger higher melting points than covalent bonds B ionic compounds have attractive forces between ions are stronger higher melting points than attractive forces between molecules C ionic compounds have ionic bonds are weaker lower melting points than covalent bonds D ionic compounds have attractive forces between ions are weaker lower melting points than attractive forces between molecules

1 marks

Answer: B

This question in 0653/22 Oct/Nov 2022

14 The structures of three molecules are shown. water ethanol methane How many atoms are in each molecule? water ethanol methane A 2 3 2 B 2 4 5 C 3 3 2 D 3 9 5

1 marks

Answer: D

This question in 0653/22 Feb/March 2023

14 The formulae of three substances are shown. substance formula methane CH4 water H2O oxygen O2 Which statement is correct? A Methane is made from five different types of atom. B Methane, water and oxygen are molecules. C Only methane and water are molecules. D Oxygen is made from two different types of atom.

1 marks

Answer: B

This question in 0653/22 May/June 2023

16 Which dot-and-cross diagram represents the outer shell electrons in a nitrogen molecule? A B N N N N C D N N N N

1 marks

Answer: A

This question in 0653/21 Oct/Nov 2023

14 Substance X is an element. It is a gas at room temperature. It is made of X2 molecules. Which diagram represents X? A B C D

1 marks

Answer: C

This question in 0653/22 Oct/Nov 2023

16 Which statement about the boiling points of covalent compounds such as CO2 and ionic compounds is correct? A These covalent compounds have higher boiling points than ionic compounds because covalent bonds are stronger than ionic bonds. B These covalent compounds have higher boiling points than ionic compounds because the attractive forces between covalent molecules are stronger than the attractive forces between ions. C Ionic compounds have higher boiling points than these covalent compounds because ionic bonds are stronger than covalent bonds. D Ionic compounds have higher boiling points than these covalent compounds because the attractive forces between ions are stronger than the attractive forces between covalent molecules.

1 marks

Answer: D

This question in 0653/22 Oct/Nov 2023

14 Which diagram represents a covalent molecule containing three different types of atom? A B H H C O H Na+ SO4 2– Na+ H C D O K+ K+ H H O2–

1 marks

Answer: A

This question in 0653/23 Oct/Nov 2023

16 Which statement about the melting points of aluminium oxide, Al 2O3, and methanol, CH3OH, is correct? A Aluminium oxide has a higher melting point than methanol because ionic bonding is stronger than covalent bonding. B Aluminium oxide has a higher melting point than methanol because the attraction between ions is stronger than the attraction between molecules. C Methanol has a higher melting point than aluminium oxide because covalent bonding is stronger than ionic bonding. D Methanol has a higher melting point than aluminium oxide because the attraction between molecules is stronger than the attraction between ions.

1 marks

Answer: B

This question in 0653/23 Oct/Nov 2023

16 Which statement describes the formation of ions when two different atoms combine? A The two atoms share a pair of electrons. B Both atoms lose electrons. C Both atoms gain electrons. D One atom gains electrons and one loses electrons.

1 marks

Answer: D

This question in 0653/22 May/June 2024

17 Which statement about covalent compounds is correct? A They are formed between a metal and a non-metal. B They are formed when atoms gain or lose electrons. C They are formed when atoms share pairs of electrons. D They conduct electricity when they are molten.

1 marks

Answer: C

This question in 0653/23 May/June 2024

16 Which dot-and-cross diagram represents the bonding in a molecule of ethene? A B C D H H H H H H H C C H H C C H C C C C H H H H H H

1 marks

Answer: D

This question in 0653/23 Oct/Nov 2024

17 Which dot-and-cross diagram shows the outer-shell electrons in a molecule of carbon dioxide? A B C D O C O O C O O C O O C O

1 marks

Answer: A

This question in 0653/22 Feb/March 2025

19 The apparatus shown is used to test a property of compound R. lamp beaker pure water The lamp does not light when the beaker contains pure water. When compound R is dissolved in the water, the lamp lights. Which row describes compound R? type of bonding elements of compound R A covalent a metal and a non-metal B covalent non-metals only C ionic non-metals only D ionic a metal and a non-metal

1 marks

Answer: D

This question in 0653/22 Feb/March 2025

15 Which statement describes a substance that contains covalent bonds? A It is a coloured compound that contains a transition element. B It is a good conductor of electricity when molten. C It is a compound formed from two non-metallic elements. D It can be broken down by the passage of an electric current.

1 marks

Answer: C

This question in 0653/22 May/June 2025

16 Which dot-and-cross diagram represents the arrangement of outer-shell electrons in a molecule of nitrogen? A B N N N N C D N N N N

1 marks

Answer: A

This question in 0653/22 May/June 2025

21 The diagrams show molecules of three of the main gases in clean, dry air. The different circles represent atoms of different elements. Which elements are shown as and ? A hydrogen nitrogen B hydrogen oxygen C oxygen hydrogen D oxygen nitrogen

1 marks

Answer: D

This question in 0653/21 Oct/Nov 2025

16 In which molecule are 10 electrons used to form covalent bonds? A C2H4 B CH3OH C CO2 D N2

1 marks

Answer: B

This question in 0653/22 Oct/Nov 2025

15 In water, hydrogen atoms and oxygen atoms are bonded together with covalent bonds. O H H Which row shows information about the electrons in a molecule of water? number of electrons number of electrons total number of in the outer shell of in the outer shell of electrons in one each hydrogen atom the oxygen atom molecule of water A 2 6 8 B 2 8 10 C 8 6 14 D 8 8 16

1 marks

Answer: B

This question in 0653/23 Oct/Nov 2025