Chemical Bonds and Types of Chemical Reactions

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

1. Q1.Sodium chloride is held together by:

   • A.covalent bonds
   • B.ionic bonds✓ Correct Answer
   • C.metallic bonds
   • D.hydrogen bonds

   Explanation: Sodium transfers an electron to chlorine.

2. Q2.A covalent bond is formed by:

   • A.sharing of electrons✓ Correct Answer
   • B.transfer of protons
   • C.transfer of neutrons
   • D.attraction between nuclei

   Explanation: Atoms share pairs of electrons to complete their outer shells.

3. Q3.Rusting of iron is an example of:

   • A.reduction only
   • B.oxidation✓ Correct Answer
   • C.sublimation
   • D.neutralisation

   Explanation: Iron reacts with oxygen and moisture.

4. Q4.Burning of magnesium ribbon in air is a:

   • A.combination reaction✓ Correct Answer
   • B.decomposition reaction
   • C.displacement reaction
   • D.neutralisation reaction

   Explanation: Magnesium combines with oxygen to form magnesium oxide.

5. Q5.The chemical formula of water is:

   • A.H2O2
   • B.HO
   • C.H2O✓ Correct Answer
   • D.H3O

   Explanation: Two hydrogen atoms bond to one oxygen atom.

6. Q6.Photosynthesis is:

   • A.an endothermic reaction✓ Correct Answer
   • B.an exothermic reaction
   • C.a neutralisation reaction
   • D.a nuclear reaction

   Explanation: It absorbs light energy.

7. Q7.Ionic compounds generally have:

   • A.low melting points
   • B.no charge
   • C.gas state at room temperature
   • D.high melting and boiling points✓ Correct Answer

   Explanation: Strong electrostatic forces hold the ions together.

8. Q8.In an oxygen molecule (O2) the atoms are joined by a:

   • A.single bond
   • B.double bond✓ Correct Answer
   • C.triple bond
   • D.ionic bond

   Explanation: Each oxygen atom shares two electrons.

9. Q9.In a nitrogen molecule (N2) the atoms are joined by a:

   • A.single bond
   • B.double bond
   • C.triple bond✓ Correct Answer
   • D.ionic bond

   Explanation: The triple bond makes nitrogen very unreactive.

10. Q10.Respiration in living cells is:

    • A.an endothermic reaction
    • B.a displacement reaction
    • C.a precipitation reaction
    • D.an exothermic reaction✓ Correct Answer

    Explanation: Glucose is oxidised and releases energy.

11. Q11.Heating calcium carbonate to give calcium oxide and carbon dioxide is a:

    • A.combination reaction
    • B.displacement reaction
    • C.decomposition reaction✓ Correct Answer
    • D.neutralisation reaction

    Explanation: One compound breaks into simpler substances.

12. Q12.Iron placed in copper sulphate solution turns the solution green and deposits copper. This is a:

    • A.decomposition reaction
    • B.combination reaction
    • C.displacement reaction✓ Correct Answer
    • D.double decomposition reaction

    Explanation: The more reactive iron displaces copper.

13. Q13.A catalyst:

    • A.is used up completely
    • B.slows every reaction
    • C.changes the products always
    • D.speeds up a reaction without being consumed✓ Correct Answer

    Explanation: It provides an alternative path with lower activation energy.

14. Q14.In terms of electrons, oxidation is:

    • A.gain of electrons
    • B.sharing of protons
    • C.loss of electrons✓ Correct Answer
    • D.gain of neutrons

    Explanation: Remember OIL RIG: oxidation is loss, reduction is gain.

15. Q15.Mixing silver nitrate and sodium chloride solutions gives a white:

    • A.gas of chlorine
    • B.solution of silver
    • C.flame
    • D.precipitate of silver chloride✓ Correct Answer

    Explanation: Silver chloride is insoluble in water.

16. Q16.Which of the following has a covalent bond?

    • A.hydrogen chloride (HCl)✓ Correct Answer
    • B.sodium chloride (NaCl)
    • C.potassium chloride (KCl)
    • D.magnesium oxide (MgO)

    Explanation: HCl shares a pair of electrons between H and Cl, while the others are ionic.

17. Q17.The unusually high boiling point of water is due to:

    • A.ionic bonding
    • B.hydrogen bonding✓ Correct Answer
    • C.metallic bonding
    • D.nuclear forces

    Explanation: Water molecules attract each other through O-H···O bonds.

18. Q18.In a coordinate (dative) bond, the shared pair of electrons is:

    • A.donated equally by both atoms
    • B.donated by one atom only✓ Correct Answer
    • C.absent
    • D.taken from the nucleus

    Explanation: Ammonium ion formation is an example.

19. Q19.In the Haber process for ammonia, the catalyst used is:

    • A.iron✓ Correct Answer
    • B.platinum
    • C.nickel
    • D.vanadium pentoxide

    Explanation: Nitrogen and hydrogen combine at high pressure over finely divided iron.

20. Q20.Le Chatelier's principle predicts how a system at equilibrium responds to:

    • A.a change in its colour only
    • B.the passage of time alone
    • C.the shape of the container
    • D.a change in conditions such as concentration, pressure or temperature✓ Correct Answer

    Explanation: The system shifts to oppose the imposed change.