Explanation:​
C3H8​ is a saturated alkane and C3H6​ is an unsaturated alkene. The test of unsaturation using Br2(aq) can demonstrate the presence or absence of a carbon-carbon double bond.
In the presence of a double bond, Br2(aq) can add across the double bond in the alkene producing a dibromo-alkane, and a change of color from brown to colorless will be observed.
In the case of the absence of a double bond (saturated hydrocarbon), no color change would occur.

Explanation​:
By definition, the more readily an acid releases a proton, the less likely the conjugate base is to accept a proton.

Explanation:​
$\mathrm{pH}$ = $-$.
For concentrations of H+ greater than 1 mol dm^−3, this would result in a negative $\mathrm{pH}$ value.

Explanation​:
NaOH is a strong base and so would release a high concentration of OH^− ions in water. Choices A and C are incorrect as HCl and H2SO4 are strong acids and would give low $\mathrm{pH}$s. $\mathrm{NaCl}$ is a neutral salt.

Explanation:​
The conjugate base of HCl is the compound produced when a hydrogen ion is removed. The conjugate base is therefore the chloride ion, Cl^−.
This question is hard as the student must link the names of chemicals to their formula and identify a conjugate base without the aid of an explicit reaction equation.

Explanation:
Use the mnemonic CNAP; cathode negative, anode positive for the polarity in electrolytic cells.

Explanation​:
In electrolysis the positive electrode is the anode. Oxidation takes place at the anode.

Explanation:​
Assuming "x" to be the oxidation number of N:

• In nitrate NO3− , x +3 (-2) = -1. Therefore, x = +5
• In nitrite NO2− , x +2 (-2) = -1. Therefore, x = +3

Explanation:​
In equation 1, the oxidation state of Cl decreases from +5 to 0 (reduced), and the oxidation state of Iodine increases from 0 to +5 ( oxidized).
In equation 2, the oxidation state of Cl increases from 0 to +1 in NaClO (oxidized), and also decreases from 0 to -1 in NaCl (reduced).

Explanation:​
A conjugate acid-base pair differ by a single hydrogen ion. Carbonic acid and carbonate (choice A) differ by two hydrogen ions so are not a conjugate acid-base pair. Boric acid and its hydroxide adduct (choice B) differ by a hydroxide ion and ammonia and hydroxylamine (choice D) by an oxygen atom.
This question is categorised as very hard as the student must recall the definition of a conjugate acid-base pair, interpret the structural formulas of unfamiliar molecules and identify a conjugate acid and base without the aid of a reaction equation.

Explanation:​

Acids react with carbonates to produce a salt, water, and carbon dioxide.

Explanation​:
By definition an acid is a proton donor. Weak acids only partially dissociate in aqueous solution leading to poor conductivity

Explanation:
Non-spontaneous reactions take place in electrolytic cells using an external power supply.
The positive electrode is the anode where oxidation takes place.
The aqueous metal ion (Mx^+) is reduced at the cathode to produce the solid metal.

Explanation​:
In this nucleophilic substitution reaction, the hydroxide donates a lone pair to break the C-Br bond and form a new C-O bond. The C atom of compound B accepts the electron pair, so is an electrophile.
The compound is a secondary bromoalkane, as the C atom of the C-Br bond is attached to two C atoms.

A

Explanation:​
NaOH is a base so reacts with a hydrogen ion. HNO3​, nitric acid, releases a hydrogen ion through the breaking (heterolysis) of the O-H bond.
This question is moderately difficult as the student must recognise that NaOH is a base and HNO3​ an acid and correctly interpret a structural formula that may be unfamiliar.

Explanation​:
Metal oxides produce basic solutions when dissolved in water. Non-metal oxides produce acidic solutions when dissolved in water.
Silicon dioxide does not react with water, but reacts with concentrated alkalis to form silicates: SiO2(s)+2 OH−(aq)→SiO32−(aq)+H2O(l)

Explanation:​
Spontaneous reactions occur in voltaic cells converting chemical energy to electrical energy, whereas, non-spontaneous reactions occur in electrolytic cells requiring electrical energy and converting this to chemical energy.
Electrolytic cells typically consist of one reaction vessel containing the aqueous of molten electrolyte. No salt bridge is therefore required.

Explanation:​
A nucleophile is a species that is electron-rich and an electron donor. An electrophile is an electron deficient species.

Explanation:​
The HPO^4− ion contains two negatively charged oxygen atoms which can bond to hydrogen ions, producing phosphoric acid (H3PO^4​).
The HPO^4− ion can therefore react with two H+ ions.
This question is moderately difficult as the student must recognise that H^+ ions bond to the negatively charged oxygen atoms, or that HPO^4− is derived from H3PO^4​.

Explanation:​
A secondary alcohol is a compound in which the carbon attached to the hydroxyl group is also attached to two other carbons.
Upon its oxidation, a removal of 2H atoms occurs and a ketone is formed.

Explanation​:
Mg(s) loses electrons to produce $).$ Loss of electrons is oxidation which takes place at the anode.

Explanation​:
The positive ions (cations) move in the direction of the cathode as the positive Cu2+ ions are used up.
Zn being more reactive than copper, Zn(s) is the anode where oxidation occurs, and Cu(s) is the cathode where reduction of Cu2+(aq) occur

Explanation​:
Statement II is incorrect as acids produce solutions with pH lower than 7.