What are the answers to these chemistry questions?

Here are the solutions to the chemistry questions from the image:

Question 1:
A subatomic particle that is positively charged is a proton.

• A. Hydrogen ion ($\text{H}^+$) is an ion, not a fundamental subatomic particle.
• B. Electron is negatively charged.
• C. Proton is positively charged.
• D. Neutron has no charge.

The final answer is $\boxed{\text{C}}$.

Question 2:
Metals less reactive than carbon can be extracted from their oxides by heating with carbon. Iron is less reactive than carbon.

• A. Aluminium is more reactive than carbon.
• B. Iron can be obtained by heating its oxide with carbon.
• C. Sodium is more reactive than carbon.
• D. Magnesium is more reactive than carbon.

The final answer is $\boxed{\text{B}}$.

Question 3:
Transition metals typically form coloured ions in solution. Manganese is a transition metal.

• A. Manganese forms coloured ions (e.g., $\text{Mn}^{2+}$ is pale pink, $\text{MnO}_4^-$ is purple).
• B. Nitrogen is a non-metal.
• C. Sulphur is a non-metal.
• D. Magnesium is an alkaline earth metal and forms colourless ions ($\text{Mg}^{2+}$).

The final answer is $\boxed{\text{A}}$.

Question 4:
Sublimation is the process where a solid turns directly into a gas without passing through a liquid phase.

• A. Limestone ($\text{CaCO}_3$) decomposes on heating.
• B. Sodium Chloride ($\text{NaCl}$) melts.
• C. Copper (II) sulphate pentahydrate loses water of crystallization.
• D. Ammonium chloride ($\text{NH}_4\text{Cl}$) sublimes on heating.

The final answer is $\boxed{\text{D}}$.

Question 5:
The kinetic theory of matter states that matter is composed of tiny particles that are in constant random motion.

• A. This describes general properties of matter.
• B. This describes atomic structure.
• C. This statement accurately describes the core idea of the kinetic theory.
• D. This describes states of matter, not the theory itself.

The final answer is $\boxed{\text{C}}$.

Question 6:
Alkanes are saturated hydrocarbons and primarily undergo substitution reactions, where a hydrogen atom is replaced by another atom.

• A. Hydrogenation is for unsaturated compounds.
• B. Substitution is a characteristic reaction of alkanes (e.g., halogenation).
• C. Addition is for unsaturated compounds.
• D. Combustion is a general reaction for many organic compounds.

The final answer is $\boxed{\text{B}}$.

Question 7:
The manufacture of sulphuric acid (Contact Process) involves several steps.

• A. This is a use of sulphuric acid, not a manufacturing step.
• B. Dissolving sulphur trioxide in water to give oleum is incorrect; $\text{SO}_3$ is dissolved in concentrated $\text{H}_2\text{SO}_4$ to form oleum.
• C. Burning of sulphur dioxide to give sulphur trioxide ($\text{2SO}_2 + \text{O}_2 \xrightarrow{\text{V}_2\text{O}_5} \text{2SO}_3$) is a key step in the Contact Process.
• D. Oleum is diluted with water to give sulphuric acid, not catalytically oxidized.

The final answer is $\boxed{\text{C}}$.

Question 8:
When sodium is dropped in ethanol, it reacts to produce hydrogen gas (causing effervescence) and sodium ethoxide ($\text{CH}_3\text{CH}_2\text{ONa}$), which is a strong base.

• A. Sodium reacts, it doesn't just dissolve.
• B. Effervescence occurs, but hydrogen gas is not pungent.
• C. The resulting solution is alkaline due to sodium ethoxide, so it turns red litmus paper blue. This is a correct observation.
• D. Sodium ethoxide is produced, not sodium hydroxide.

The final answer is $\boxed{\text{C}}$.

Question 9:
Polythene (polyethylene) is widely used for making plastic bags and is also an excellent electrical insulator.

• A. Terylene is used for fabrics and bottles.
• B. Polythene is suitable for packaging bags and electrical insulation.
• C. Polystyrene is used for disposable cups and insulation boards.
• D. Nylon is used for fibers and ropes.

The final answer is $\boxed{\text{B}}$.

Question 10:
Electrolysis is a key process in the manufacture of certain heavy chemicals, particularly strong bases and reactive metals/non-metals.

• A. Sodium hydroxide ($\text{NaOH}$) is manufactured by the electrolysis of brine (chlor-alkali process).
• B. Sulphuric acid ($\text{H}_2\text{SO}_4$) is made by the Contact Process, which does not involve electrolysis.
• C. Nitric acid ($\text{HNO}_3$) is made by the Ostwald process, which does not involve electrolysis.
• D. Copper ($\text{Cu}$) is extracted from ores, often refined by electrolysis, but $\text{NaOH}$ is a more direct fit for "manufacture involves electrolysis" as a primary production method for the bulk chemical.

The final answer is $\boxed{\text{A}}$.

Question 11:

• "Evolve steamy white fumes with $\text{PCl}_5$" indicates the presence of an -OH group (alcohol or carboxylic acid).
• "Equally evolve a colourless gas with sodium carbonate" indicates the presence of a carboxylic acid group (-COOH), as carboxylic acids react with carbonates to produce $\text{CO}_2$ gas. Alcohols do not react with sodium carbonate. Therefore, we are looking for a carboxylic acid.
• A. $\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}$ is an alcohol.
• B. $\text{CH}_3\text{CH}=\text{CH(OH)}$ is an unstable enol.
• C. $\text{CH