AQA Chemistry Paper 1 Practice Quiz 2019

A chemical formula conveys the types and the relative numbers of each type of atom in a compound. It does not provide information about physical state, reaction mechanisms, or electron configurations.

Isotopes are versions of the same element that have identical numbers of protons but vary in the number of neutrons. This results in different atomic masses without a significant change in chemical properties.

Ionic bonds are created when electrons are transferred between atoms, resulting in the formation of oppositely charged ions that attract each other. Other bonding types involve sharing electrons or different types of electron interactions.

A mole is a standard unit in chemistry used to count particles, defined as 6.022 x 10^23 particles. It links the atomic scale with measurements used in the laboratory.

Rusting of iron is a chemical change because it transforms iron into a new substance (iron oxide) through a chemical reaction. The other examples involve physical changes where the chemical identity remains the same.

As you move across a period, the increasing nuclear charge pulls electrons closer to the nucleus, thereby reducing the atomic radius. This trend is consistent despite the addition of electrons since the effective nuclear charge increases.

Fluorine is highly electronegative and has a strong tendency to gain an electron to achieve a stable electron configuration. The other elements typically lose electrons to form cations rather than gaining them.

Covalent bonding involves the sharing of electrons between atoms in order to achieve a stable electron configuration. This is different from ionic bonding, where electrons are transferred, and metallic bonding, which involves delocalized electrons.

The reaction shows two reactants combining to form a single product, fitting the definition of a synthesis or combination reaction. The other reaction types involve breaking down compounds or exchanging parts which is not the case here.

Oxidation state is a useful book-keeping tool that shows the degree of oxidation of an atom in a compound, as if the bonding were purely ionic. It does not refer to the actual number of neutrons, the electron configuration, or the atomic mass.

Increasing the concentration of reactants typically enhances the frequency of collisions, which in turn increases the reaction rate. This is based on collision theory and assumes that other conditions, such as temperature, remain constant.

Water is an amphoteric substance, which means it can act either as an acid or a base depending on the reaction conditions. The other substances are generally characterized by a single type of chemical behavior.

Hydrogen bonds, which form between the hydrogen atom of one water molecule and the oxygen atom of another, are primarily responsible for water's unusually high boiling point. While dispersion and dipole-dipole forces exist, they are not as strong as hydrogen bonding in water.

Noble gases are characterized by having complete valence shells, which makes them stable and largely unreactive. The other configurations indicate a tendency to gain, lose, or share electrons to reach stability.

A catalyst speeds up a reaction by providing an alternative pathway with a lower activation energy, thereby increasing the reaction rate. Importantly, it does not alter the reaction temperature, reactant concentrations, or the equilibrium position.

Percent yield is calculated by dividing the actual yield by the theoretical yield and then multiplying by 100. In this case, (10/12.5) x 100 equals 80%, making it the correct answer.

First, 14 grams of N₂ equals 0.5 moles (14/28). The balanced equation shows that 1 mole of N₂ produces 2 moles of NH₃, so 0.5 moles of N₂ gives 1 mole of NH₃, which has a mass of 17 grams. Therefore, 17 grams of NH₃ should form.

The electron configuration given shows 7 electrons in the outer shell, which is characteristic of halogens found in Group 17. This arrangement leads to high reactivity as the element seeks to gain one electron.

A catalyst speeds up both the forward and reverse reactions equally, so it does not alter the position of equilibrium. Its function is solely to reduce the activation energy required for the reaction.

According to Boyle's Law, pressure and volume are inversely proportional when temperature is constant. Halving the volume from 22.4 L to 11.2 L results in doubling the pressure from 1 atm to 2 atm.