Explanation:
The longest carbon chain has 5 carbons and will include the C=C.
The alkene is given priority and is on carbon-1.
The methyl group is bonded to carbon-2.

Explanation:
Amides have a C=O and C−N on the same central carbon atom.

Explanation:

The electron configuration of the atom is 1s^2 2s^2 2p^4. There are 8 electrons in total and the electron configuration corresponds to a neutral atom, so the atomic number must be 8 also. The element is oxygen and it lies in group 16 $\text{OR}$ since the atom has 6 valence electrons, its element should be located in group 16.

There are two subshells so the period number is 2. This question is moderately difficult as the student must deduce that the number of electrons is equal to the atomic number or determine which of the orbitals are part of different shells, without the assistance of orbital labels.

Explanation:
The masses of options A, B, C and D are 29, 45, 31 and 28, respectively.
The mass of the fragment ion is 148 - 117 = 31, making option C correct.
This question is of moderate difficulty as two simple calculations are required

Explanation:
NH2 is the amine functional group, RCOOR′ is the ester functional group.

Explanation:
Statement III is not correct as physical properties, including melting point and metallic character, change dramatically across a period due to changes in nuclear charge for the same number of shells.
Elements in the periodic table are arranged in increased atomic number.
Anions are atoms that have gained electrons. This will increase the electron-electron repulsion in the outermost shell, and will cause the electrons to move further apart.Therefore, the radius of the outershell will increase.

Explanation:
The 6 protons in the nucleus of carbon will exert a stronger attractive force on the second energy level electrons than the 5 protons of boron.
Increasing electron affinity from left to right across a period.

Explanation:
Increasing atomic radius results in a weaker electrostatic force of attraction between the nucleus and electrons in the covalent bond. An increased number of shells down the group increases the shielding between the nucleus and electrons in the covalent bond.

Explanation:
1 and 2 are enantiomers, exhibiting opposite optical activities (rotate plane polarised light in opposite directions by the same amount).
Compound 3 is achiral, so it has a rotation angle of 0 degrees.
This question is in the “hard” category, as the student must be able to determine a molecule's chirality and recall how polarimetry can be used to distinguish between stereoisomers.

Explanation:
There are 4 proton environments as the CH(CH3)2 protons are equivalent. Integration gives the relative number of protons in each environment. There are 3 on C1, 2 on C2, 1 of C3 and 6 on C4 and 5.

Explanation:
Saturated compounds contain only single bonds.
Butyne is an alkyne, and so, has a triple bond.

Explanation:
Acid rain is formed from sulfur and nitrogen oxides dissolving in the clouds.

Explanation:
Ligands are Lewis bases with a lone pair of electrons that they can donate to a central metal ion.

Explanation:
Atomic radius and metallic character decrease across a period. Ionization energy decreases down a group due to increased shielding.

Metalloids lie on the boundary between metals and non-metals in the p block of the periodic table. They are shiny like metals but brittle like non-metals, and can switch between being electrical insulators and electrical conductors. Although this switchable conductivity could be considered as a change from metal-like to non-metal-like behaviour, it does not affect all properties of the element: the element does not switch from being a metal to a non-metal.

Metalloids do not contain incomplete d subshells (this is a property of transition metals) and lie alongside the poor metals in the p block of the periodic table. This question is categorised as moderately difficult as the concept of metalloids is not covered extensively in the syllabus, though the distinction between metals, non-metals and metalloids is highlighted.

Explanation:

The group of an element is determined by its atomic number, which is found in the lower left corner of the element symbol. Although this conflicts with the representation in the data booklet, students should be able to differentiate between the mass and atomic number based on their relative size. The elements represented by options A, B, C and D are calcium (an alkaline earth metal), iron (a transition metal), gallium (a poor / p block metal) and rubidium (an alkali metal), respectively. This question is moderately difficult as the student must identify the correct value from the given symbol and relate it to the position of an element in the periodic table.

Explanation:
Strontium is in group 2 and so forms Sr^2+ ions. The formula of the sulfide ion is S^2− as sulfur is in group 16. For the positive and negative charges to cancel out, one of each ion is required.

Explanation:
The electron configuration of Zn2+ is [Ar] 3d^10. There are no vacancies in the $d$ subshell so a transition between the split energy levels of the octahedral complex is not possible.
This question is categorized as easy as the colourless nature of d10 ions is covered explicitly in the syllabus.

Explanation:
Statement II is incorrect as acids produce solutions with $\mathrm{pH}$ lower than 7

Explanation:
Across the same period, metals have lower ionization energies than non-metals due to lower nuclear charges with the same number of shells (shielding effect).

Explanation:
The methyl groups are equivalent so produce one signal with integral 6, while the other protons both produce signals with integrals 1.
The student must recognise that all protons are detectable by NMR, including those attached to $\mathrm{O}$ atoms, and know how to count proton environments (COOH protons are sometimes too broad to detect due to proton exchange and/or hydrogen bonding, but this point is not covered at IB level).
The question is categorised as hard as several features of the $\mathrm{NMR}$ spectrum must be predicted.

Explanation:
The charges of the positive and negative ions must cancel out to give an overall neutral compound. Group 2 metals form ions with a 2+ charge. The formulae of the counterions above are: $.$

Explanation:
Each $\mathrm{Cl}$ ligand has a 1-charge.
2+(4x−1)=2−.
As outlined in the Chemistry Guide, [CuCl4]^2− has a tetrahedral shape.