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The sulphide that is generally considered insoluble in dilute hydrochloric acid is copper sulphide (CuS). While many metal sulphides dissolve in dilute HCl, copper sulphide is one of the few that remains undissolved due to its relatively low solubility product. When CuS is added to dilute HCl, no visible reaction occurs, indicating its insolubility. In order to dissolve copper sulphide, a stronger acid like nitric acid (HNO3) is typically required.

The correct answer is D. Conversion of silver halides to grey metallic silver. This reaction is a classic example of a photochemical reaction: 2AgCl (silver chloride) + light energy → 2Ag (silver) + Cl₂ (chlorine) In this reaction, light energy (typically ultraviolet or visible light) initiates the decomposition of silver chloride into silver metal and chlorine gas. This reaction is commonly used in photographic film and paper.

The organic material (or organics) within the low-oxygen environment of landfills also undergoes anaerobic digestion, producing methane. When organic matter decomposes without oxygen (anaerobic conditions), bacteria produce a gas mixture called biogas, which is mainly composed of methane and carbon dioxide.

The correct answer is A. Low sulphur content. Nigerian crude oil is classified as "light" crude oil due to its relatively low density and low sulphur content. Light crude oils typically have: - API gravity > 31.1^\circ (less dense) - Low sulphur content (< 1%) - High API gravity indicates a lower density and a higher proportion of lighter hydrocarbons Crude oil is called "light crude" when it has a low density, meaning it is less viscous and easier to refine, typically indicated by a high American Petroleum Institute (API) gravity value, which signifies that the oil is lighter than water and will float on it; essentially, it contains a higher proportion of lighter hydrocarbon fractions making it more valuable for producing gasoline and other lighter products compared to heavier crude oils. Crude oils are said to be sweet because they have low sulphur content. The low sulphur content makes Nigerian crude oil more desirable for refining into petroleum products, as it requires less processing to remove impurities.

Unsaturated hydrocarbons are organic compounds that are entirely made up of carbon and hydrogen atoms and consist of a double or a triple bond. Unsaturated hydrocarbons are compounds composed of carbon and hydrogen atoms, with one or more carbon-carbon double or triple bonds in their chemical structure. In other words, unsaturated hydrocarbons are the Alkenes(C=C) and the Alkynes (C≡C). Hence, propene is the only alkene member in the given options.

The molecule C4H10 has two isomers. These are commonly known as "butane" and "isobutane". C4H10 represents a four-carbon alkane, and the only structural variations possible are a straight chain (n-butane) and a branched chain (isobutane) or 2-methylpropane.

In the molecule CH3-CH2-C≡CH, the hybridization of the carbon atoms are: sp3 for the first carbon (CH3), sp3 for the second carbon (CH2), sp for the third carbon (C≡C), and sp for the fourth carbon (C≡CH). sp3 hybridization: The first and second carbon atoms are each bonded to four other atoms (three hydrogen atoms and one carbon atom), so they are sp3 hybridized. sp hybridization: The third and fourth carbon atoms are involved in a triple bond, which requires the use of sp hybrid orbitals to form the strong sigma bond and two pi bonds. Key points to remember: A carbon atom with single bonds to four other atoms is sp3 hybridized. A carbon atom with one double bond and two single bonds is sp2 hybridized. A carbon atom with a triple bond and one single bond is sp hybridized.

2VD = Rmm VD = Vapour density; Rmm - Relative 2 * 20 = 40 Molecular mass Mole of carbon = 36/12 = 3 Mole of H2 = 40 - 36 = 4 The compound contains 3 mole of carbon and 4 hydrogen

The correct answer is C. Palm oil. An emulsion is a mixture of two or more liquids that don't normally mix, such as oil and water. Detergents can help stabilize emulsions. Palm oil is an oil that can be emulsified with water using a detergent solution. When you shake a detergent solution with palm oil, the detergent molecules can help stabilize the mixture, creating an emulsion. The other options won't produce an emulsion: A. Palm wine is a liquid that's already miscible with water. B. Ethanoic acid (acetic acid) is a polar solvent that's miscible with water. D. Water is already a component of the detergent solution, so shaking it with more water won't create an emulsion.

The heat of the flame vaporizes the liquid wax (turns it into a hot gas), and starts to break down the hydrocarbons into molecules of hydrogen and carbon. These vaporized molecules are drawn up into the flame, where they react with oxygen from the air to create heat, light, water vapor (H\(_2\)O) and carbon dioxide (CO\(_2\)).

Given: Volume of solvent, V = 50cm\(^3\) Molar mass, M = 342g Mass of solute, m = 34.2g Solubility = ? Solubility = \(\frac{mass}{molar mass}\times\)\(\frac{1000}{Volume of solvent}\) = \(\frac{34.2}{342}\times\)\(\frac{1000}{50}\) = 2 moldm\(^{-3}\)

The correct answer is C. Oxides of sulphur. Acid rain is formed when pollutants in the atmosphere, such as sulphur dioxide (SO₂) and nitrogen oxides (NOx), react with water, oxygen, and other chemicals to form acidic compounds. These compounds can then fall to the ground as precipitation, resulting in acid rain. Sulphur dioxide (SO₂) is a major contributor to acid rain. When SO₂ is released into the atmosphere, it can react with water and oxygen to form sulphuric acid (H₂SO₄), which is a strong acid: SO₂ + H₂O + 1/2O₂ → H₂SO₄ The other options are not directly responsible for acid rain: A. Oxides of lead are toxic pollutants, but they don't contribute to acid rain. B. Particulate matter can be a pollutant, but it's not directly involved in acid rain formation. D. Gaseous hydrocarbons can contribute to smog and other air quality issues, but they're not a primary cause of acid rain.

Water is considered a "universal solvent" because of its polar molecular structure, which allows it to dissolve a wider range of substances than most other liquids due to its ability to interact with both positive and negative charges of other molecules, effectively breaking them apart and dissolving them in water; essentially, it can dissolve more substances than any other liquid.

The correct answer is D. Saturated. When a crystal of a salt is added to a saturated solution of the same salt, the crystal does not dissolve, and the solution remains unchanged. This indicates that the solution has reached its maximum capacity to dissolve the salt, and no more salt can be dissolved. A saturated solution is a chemical equilibrium state where the rate of dissolution of the solute equals the rate of precipitation. In this case, the solution is already holding as much dissolved salt as it can, so the added crystal doesn't dissolve. The other options are not correct: A. Supersaturated solutions are unstable and can't persist indefinitely. If a crystal were added to a supersaturated solution, it would trigger precipitation. B. Concentrated solutions have a high amount of solute dissolved in the solvent, but this doesn't necessarily mean the solution is saturated. C. Unsaturated solutions have the capacity to dissolve more solute. If a crystal were added to an unsaturated solution, it would dissolve.

Given: n(P) = 11 n(N) = 12 n(e-) = 10 \(^{23}_{11}\) X \(^+\) ⇒ The positive sign shows that it is a metallic ion because all metals are positively charged.