Explanation:

The names of the labelled groups are covered explicitly in the syllabus.

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: NH4+,Cl−,SO4^2−,and PO4^3−

Explanation:
The two compounds are part of a homologous series because they have the same functional group but different hydrocarbon chains. Both compounds are alcohols, so interact via hydrogen bonding.
The CH2 and CH3 groups of the alkyl chains, however, interact via weaker dispersion forces, as they contain only non-polar bonds. Increasing the length of the alkyl chain does not affect the strength of hydrogen bonding, but the strength of the dispersion forces is increased. More heat energy is needed to separate molecules of Y, so the boiling point is higher.

Explanation:
A tertiary amine is when three carbon groups are attached to the amine.

Explanation:
The number of shells and therefore the shielding effect is the same for all of these species.
As the number of protons decreases, the attraction between the nucleus and electrons decreases, resulting in a smaller radius.
K^+ has the most protons (19), whereas S^2− has the least (16).

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

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

Explanation:
The air is naturally composed of 0.04% carbon dioxide, which dissolves in water to form the weak carbonic acid

Explanation:
C3H6 belongs to the alkene class with the general formula CnH2n, and has a three carbon chain.

Explanation:
Group 17 melting points increase down the group due to increased strength in intermolecular forces. The molecular structures of each element are held together by London (dispersion) forces. These increase with the number of electrons in the molecule. Therefore statement I is not true, but III is.
Group 1 melting points decrease down a group due to decreasing metallic bond strength (with increase of atomic radius), therefore statement II is also true.

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:
First ionization energy is defined as the energy required to remove one mole of electrons from one mole gaseous atoms.

Explanation:

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:
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 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:
First ionization energy decreases down a group due to increased shielding (number of shells). Beryllium must therefore have a higher first IE than magnesium. And similarly, oxygen higher than sulfur.
First ionization energy increases across a period due to increased nuclear charge for the same number of shells. Hence, oxygen has higher first IE than beryllium.

Explanation:
The attraction for a shared pair of electrons in a covalent bond depends on electronegativity. Carbon has the lowest electronegativity value of the given elements across period 2, it has the lowest effective nuclear charge (least number of protons attracting valence electrons in energy level 2). Increasing electronegativity across a period from left to right.

Explanation:
Na^+, Ne, O^2−have 10 electrons in two energy levels with 11, 10, and 8 protons respectively. The increased number of protons has a greater pull on the 10 electrons and reduces the radius.
Ca^2+ has 18 electrons in 3 energy levels and is therefore, the largest.

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

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

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

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

Explanation:
Ethers contain C−O single bonds $\text{not}$ the $\mathrm{C}=\mathrm{O}$ carbonyl group.