DP Chemistry Questionbank

Which species has bond angles of 90°?

A. AlCl₄^-

B. $\text{I}$Cl₄^-

C. NH₄⁺

D. SiCl₄

(i) Draw diagrams to show how sigma (σ) and pi (π) bonds are formed between atoms.

(ii) State the number of sigma (σ) and pi (π) bonds in propane and propene.

(i) Uranium hexafluoride, UF₆, is used in the uranium enrichment process that produces fuel for nuclear reactors.

State the molecular shape of uranium hexafluoride.

(ii) Explain why uranium dioxide, UO₂, has a very high melting point whereas uranium hexafluoride vapourises easily into gas.

Which combination correctly describes the geometry of ${{\mathrm{BrF}}_4}^{-}$?

State the number of sigma ($\mathrm{\sigma }$) and pi ($\mathrm{\pi }$) bonds around the central carbon atom in molecule B.

$\mathrm{CFC}$s produce chlorine radicals. Write two successive propagation steps to show how chlorine radicals catalyse the depletion of ozone.

State the type of hybridization shown by the central carbon atom in molecule B.

State the electron domain geometry around the nitrogen atom and its hybridization in methanamine.

Formulate two equations to show how nitrogen(II) oxide, NO, catalyses the destruction of ozone.

Suggest why the loss of ozone is an international environmental concern.

Deduce the Lewis (electron dot) structure and molecular geometry and the bond angles of PCl₃.

Discuss the bonding in the resonance structures of ozone.

Deduce one resonance structure of ozone and the corresponding formal charges on each oxygen atom.

Outline, in terms of the bonding present, why the reaction conditions of halogenation are different for alkanes and benzene.

Estimate the H−N−H bond angle in methanamine using VSEPR theory.

Ammonia reacts reversibly with water.
$$\text{N}{\text{H}}_{\text{3}}\text{(g)}+{\text{H}}_{\text{2}}\text{O(l)}\rightleftharpoons {\text{NH}}_{\text{4}}^{+}\text{(aq)}+\text{O}{\text{H}}^{-}\text{(aq)}$$
Explain the effect of adding ${\text{H}}^{+}\text{(aq)}$ ions on the position of the equilibrium.

How many sigma (σ) and pi (π) bonds are present in this molecule?

Draw the Lewis (electron dot) structures of PF₃ and PF₅ and use the VSEPR theory to deduce the molecular geometry of each species including bond angles.

Draw diagrams to show how sigma (σ) and pi (π) bonds are formed between atoms.

Which overlap of atomic orbitals leads to the formation of only a sigma (σ) bond?

       I.     s − p

       II.     p − p

       III.     s − s

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

Describe how sigma (σ) and pi ($\pi$) bonds are formed.

The C–N bonds in urea are shorter than might be expected for a single C–N bond. Suggest, in terms of electrons, how this could occur.

Deduce the number of σ and $\pi$ bonds in a molecule of ethyne.

Absorption of UV light in the ozone layer causes the dissociation of oxygen and ozone.

Identify, in terms of bonding, the molecule that requires a longer wavelength to dissociate.

Carbon dioxide can be represented by at least two resonance structures, I and II.

Calculate the formal charge on each oxygen atom in the two structures.

Deduce, giving a reason, the more likely structure.

Which molecules contain two pi ($\mathrm{\pi }$) bonds?

I.   HCN
II.  H₂CO₃
III. H₂C₂O₄

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Distinguish between a sigma and pi bond.

What is the number of sigma (σ) and pi (π) bonds in the molecule (NC)₂C=C(CN)₂?

Draw two Lewis (electron dot) structures for BrO₃⁻.

What is the formal charge of the oxygen atom in H₃O⁺?

A.  −2

B.  −1

C.  0

D.  +1

State the number of $\text{σ}$ (sigma) and $\mathrm{\pi }$ (pi) bonds in Compound A.

Deduce a Lewis (electron dot) structure of the nitric acid molecule, HNO₃, that obeys the octet rule, showing any non-zero formal charges on the atoms.

Explain the relative lengths of the three bonds between N and O in nitric acid.

Identify the number of sigma and pi bonds in HCN.

Sketch the shape of one sigma ($\text{σ}$) and one pi ($\mathrm{\pi }$) bond.

Outline why both C to O bonds in the conjugate base are the same length and suggest a value for them. Use section 10 of the data booklet.

State the hybridization of the nitrogen atom in chloramine.

Dinitrogen monoxide in the stratosphere is converted to nitrogen monoxide, NO (g).

Write two equations to show how NO (g) catalyses the decomposition of ozone.

Deduce the hybridization of the central nitrogen atom in the molecule.

State what the presence of alternative Lewis structures shows about the nature of the bonding in the molecule.

How many sigma (σ) and pi (π) bonds are present in hydrogen cyanide, HCN?

When excess ammonia is added to copper(II) chloride solution, the dark blue complex ion, [Cu(NH₃)₄(H₂O)₂]²⁺, forms.

State the molecular geometry of this complex ion, and the bond angles within it.

Molecular geometry:

Bond angles: