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Alkenes decolourize potassium permanganate (KMnO\(_4\)) solution, a reaction used as a test for unsaturation, with the purple color of KMnO\(_4\) changing to a brown precipitate or a colorless solution depending on reaction conditions.

Isomers are two or more compounds having the same molecular formula but different structural formula. Among the options given, only propanal and propanone have the same number of C atoms, Hydrogen atoms and Oxygen atoms even though they have different structural formulas, their molecular formulas are the same, hence they are Isomers. Propanal - CH\(_3\)CH\(_2\)CHO ⇒ C\(_3\)H\(_6\)O Propanone - CH\(_3\)COCH\(_3\) ⇒ C\(_3\)H\(_6\)O

In the purification of ethyl ethanoate (ethyl acetate), Na₂CO₃ (sodium carbonate) solution is used to neutralize any residual acidic impurities, such as ethanoic acid, that may be present in the crude ester product. During the esterification reaction (the process of making ethyl ethanoate), some ethanoic acid (acetic acid) might remain unreacted or be formed as a byproduct. Sodium carbonate is a base, and it reacts with acids. When Na₂CO₃ solution is added to the ethyl ethanoate, it neutralizes the ethanoic acid, forming sodium ethanoate (a salt) and carbon dioxide (CO₂).

Let's consider an example: Cycloalkane → Cyclopropane has the formula CH\(_2\)-CH\(_2\)-CH\(_2\) (when drawn in a cyclic form) = C\(_3\)H\(_6\) Open chain alkane → Propane has the formula CH\(_3\)CH\(_2\)CH\(_3\) (when drawn on a straight chain) = C\(_3\)H\(_8\) Comparing the two formulas; C\(_3\)H\(_6\) and C\(_3\)H\(_8\), the difference in the hydrogen atoms is two.

Whenever equal moles of ethyne and hydrogen iodide react, the triple bond in ethyne is broken down to double bond in order to accommodate the hydrogen iodide coming in because it is an addition reaction. Let's consider the reaction below: H - C ≡ C - H + HI → H\(_2\)-C = CHI

The solid substances left behind as scale when water boilers are used in boiling water for a long period of time will contain Magnesium trioxosilicate(IV) and rust which is an indication that the water is hard water(temporary hardness of water, which upon boiling, Calcium and magnesium trioxocarbonate(IV) are formed on the ring ). The rust can occur because of the presence of oxygen and water.

Noble gases, primarily argon, make up about 1% of Earth's atmosphere, with argon being the most abundant at 0.934%. Volume of noble gases in air mixture = % composition of noble gas X Total volume of air mixture 25cm\(^3\) = 1% X V\(_T\) 25cm\(^3\) = \(\frac{1}{100}\times {V_T}\) 25cm\(^3\) = \(\frac{V_T}{100}\) V\(_T\) = 25 X 100 ∴ V\(_T\) = 2,500cm\(^3\)

A solubility curve graphically represents how the solubility of a solute (a substance that dissolves in a solvent) changes with temperature, showing the maximum amount of solute that can dissolve at a given temperature.

Smelting is a process of applying heat and a chemical reducing agents to an ore to extract a desired product. The reducing agent is commonly a fossil-fuel source of carbon, such as carbon monoxide from incomplete combustion of coke. The oxygen in the ore binds to carbon at high temperatures, as the chemical potential energy of the bonds in carbon dioxide (CO\(_2\)) is lower than that of the bonds in the ore. The main industrial uses include fossil fuel processing and ammonia production. Emerging uses for hydrogen include the use of fuel cells to generate electricity Sulphide ores such as those commonly used to obtain copper, zinc or lead, are roasted before smelting in order to convert the sulphides to oxides, which are more readily reduced to the metal. Roasting heats the ore in the presence of oxygen from air, oxidizing the ore and liberating the sulphur as SO\(_2\) gas.

kerosene can be used to dissolve oil stains on fabric, especially old or stubborn ones, as it acts as a solvent to lift the oil from the fabric. It is a petroleum-based product that has solvent properties, meaning it can dissolve or break down oil and grease.

While both SO\(_2\) and H\(_2\)S are dangerous pollutants, H\(_2\)S (hydrogen sulphide) is generally considered more dangerous to humans, especially at high concentrations, due to its rapid and potentially lethal effects on the respiratory system and central nervous system.

Pond water does contain nitrogen, in various forms like ammonia, nitrite, and nitrate, which are essential nutrients for aquatic life and play a crucial role in the pond's ecosystem. Nitrogen enters ponds through various sources, including rainfall, wind, run-off from land, and the decomposition of organic matter like leaves, twigs, and fish waste.

CaCO\(_3\) → CaO + CO\(_2\) CaCO\(_3\) = 40 + 12 + (16 x 3) = 100, CaO = 40 + 16 = 56 56g of CaO was produced by 100g of CaCO\(_3\) ∴ 5.6g of CaO will be produced by (5.6 x 100)/56 = 10g of CaCO\(_3\) Recall that Number of moles = \(\frac{mass}{molar mass}\) = \(\frac{10}{100}\) = 0.10mole Alternatively, CaCO\(_3\) → CaO + CO\(_2\) n = \(\frac{m}{M}\) n = \(\frac{5.6}{56}\) n = 0.10 mole Since the ratio of the reactant to product is 1 : 1, and the number of mole of CaO is 0.10mole, therefore, the number of mole of CaCO\(_3\) will also be 0.10 mole, according to Avogadro's law.

Methane (CH\(_4\)) has a tetrahedral shape with four equivalent C-H bonds and bond angles of 109.5 degrees. The tetrahedral shape of methane can be explained using the Valence Shell Electron Pair Repulsion (VSEPR) theory, which states that electron pairs around an atom will arrange themselves to minimize repulsion. The carbon atom in methane undergoes sp3 hybridization, meaning that it combines one s orbital and three p orbitals to form four equivalent sp3 hybrid orbitals.

In solids, the particles (atoms, molecules, or ions) are closely packed together due to strong intermolecular forces. These forces are strong enough to overcome the thermal energy of the particles, preventing them from moving freely. Strong intermolecular forces of attraction are primarily responsible for the definite shapes and volumes of solids because they hold the constituent particles in fixed positions.