Carbon And its Compounds-F

An oxidising agent (or oxidant) is a substance that adds oxygen to another substance or removes hydrogen from it. In doing so, the oxidising agent itself gets reduced. For example, potassium permanganate (KMnO₄) and potassium dichromate (K₂Cr₂O₇) are common oxidising agents. Reducing agents remove oxygen or add hydrogen. Indicators show pH change. Catalysts speed up reactions without being consumed.

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Ethanol (C₂H₅OH) contains the hydroxyl group (–OH) attached to a carbon atom. This is the functional group of alcohols. –CO– is the ketone group (carbonyl between two carbons), –CHO– is the aldehyde group, and –COOH is the carboxylic acid group. So ethanol contains –OH.

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Ethanol (C₂H₅OH) is the second member of the alcohol homologous series. The functional group of alcohols is –OH. Alkanes have only single bonds (no –OH), acids have –COOH, alkenes have double bonds (C=C). So ethanol belongs to the alcohol series. Methanol (CH₃OH), ethanol (C₂H₅OH), propanol (C₃H₇OH) are all alcohols.

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Substitution reactions are reactions in which one atom (usually hydrogen) is replaced by another atom or group. Saturated hydrocarbons (alkanes) undergo substitution reactions because they have only single bonds and are relatively stable. For example, methane reacts with chlorine to replace hydrogen atoms one by one. Unsaturated hydrocarbons (alkenes, alkynes) typically undergo addition reactions, not substitution. So substitution occurs mainly in saturated hydrocarbons.

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Ethanol (C₂H₅OH) has a melting point of -114°C and a boiling point of 78°C. At room temperature (around 25°C), it is a colourless liquid. It is not a solid (that would be below -114°C), not a plasma (extremely high temperature), and not a gas (above 78°C it boils, but at room temperature it is liquid). So liquid is correct.

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Alcohols (like ethanol) react with sodium metal to release hydrogen gas. The reaction is: 2C₂H₅OH + 2Na → 2C₂H₅ONa (sodium ethoxide) + H₂↑. This is similar to the reaction of water with sodium. Hydrogen gas is released, which can be tested by a popping sound with a burning match. Oxygen, nitrogen, and carbon dioxide are not released in this reaction.

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Methane (CH₄) reacts with chlorine (Cl₂) in the presence of sunlight to undergo substitution. The first product is chloromethane (CH₃Cl) and hydrogen chloride (HCl): CH₄ + Cl₂ → CH₃Cl + HCl. Further substitution can produce dichloromethane (CH₂Cl₂), chloroform (CHCl₃), and carbon tetrachloride (CCl₄), but the immediate product in the first step is chloromethane and HCl. Carbon dioxide is from combustion. Methanol is from oxidation.

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Long-term (chronic) consumption of alcohol leads to serious health problems including liver damage (cirrhosis), stomach ulcers, pancreatitis, heart disease, brain damage (memory loss, coordination issues), and addiction (alcoholism). It does not promote growth (it can stunt growth in adolescents), does not provide sustained energy (empty calories), and weakens immunity (does not improve it). So health problems is correct.

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Alkaline potassium permanganate (KMnO₄ in basic medium) is a strong oxidising agent. It oxidises ethanol to ethanoic acid (acetic acid). The purple colour of KMnO₄ disappears as it gets reduced. Hydrogen gas is a reducing agent. Calcium carbonate is a base/neutraliser. Sodium hydroxide is a base, not an oxidising agent. So alkaline potassium permanganate is correct.

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Vegetable oils are unsaturated fats (containing double bonds). Hydrogenation is the addition of hydrogen (H₂) across these double bonds in the presence of a catalyst (like nickel). This converts the unsaturated oils into saturated fats (like vanaspati ghee or margarine). The product is not alcohols, not exactly animal fats (though similar in saturation), and not acids. So saturated fats is correct.

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Ethanol can be used as a fuel (it is added to petrol as ethanol blend), but it is not widely used as a primary fuel because it is poisonous to humans if consumed. However, the main reason it is not used as a major fuel is economic (it is expensive to produce compared to petrol) and it can cause engine corrosion. Among the given options, “it is poisonous” is the best answer because drinking ethanol as fuel would be dangerous. It does burn with heat, it is soluble in water, so those options are wrong.

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Acidified potassium dichromate (K₂Cr₂O₇/H₂SO₄) is an oxidising agent. When ethanol is oxidised, it first forms ethanal (acetaldehyde, an aldehyde). With further oxidation, it forms ethanoic acid (carboxylic acid). For JKBOSE level, the immediate product is often given as aldehyde. The colour change from orange (dichromate) to green (Cr³⁺) indicates oxidation. Alkane and alkene are not formed. So aldehyde is correct.

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Vanaspati ghee (vegetable ghee) is made by hydrogenating vegetable oils. Hydrogen gas is passed through the oil in the presence of a nickel catalyst, adding hydrogen to the double bonds and converting unsaturated fats into saturated fats. This is called hydrogenation. Dehydration removes water, oxidation adds oxygen, substitution replaces one atom with another. So hydrogenation is correct.

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Dehydration of ethanol (removal of water) to form ethene requires heating ethanol with concentrated sulphuric acid at about 443 K (170°C). The reaction is: C₂H₅OH → C₂H₄ + H₂O. At lower temperatures (around 413 K or 140°C), diethyl ether is formed instead. 500 K is too high, 300 K is room temperature, 373 K is boiling point of water (100°C). So 443 K is correct.

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Unsaturated hydrocarbons (alkenes and alkynes) contain double or triple bonds. They undergo addition reactions, where atoms or groups are added across the multiple bond. For example, ethene adds hydrogen (hydrogenation), bromine (bromination), or water (hydration). Saturated hydrocarbons undergo substitution. Neutralisation is for acids and bases. Combustion occurs for all hydrocarbons but is not the characteristic reaction. So addition is correct.

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Ethanol (C₂H₅OH) has two carbon atoms. When fully oxidised, it produces ethanoic acid (CH₃COOH, also called acetic acid). Methanoic acid (HCOOH) has one carbon, propanoic acid (C₂H₅COOH) has three carbons, butanoic acid (C₃H₇COOH) has four carbons. The carbon chain length does not change during oxidation of an alcohol to a carboxylic acid. So ethanoic acid is correct.

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Unsaturated fatty acids (found in vegetable oils, fish oil, nuts) are considered healthier than saturated fats. They help reduce bad cholesterol (LDL) and lower the risk of heart disease. Saturated fats (found in animal fats, butter, ghee) are considered less healthy when consumed in excess. Unsaturated fatty acids are not toxic, not inert (they are reactive), and not harmful in moderation. So healthier is correct.

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Ethene (C₂H₄) has a carbon-carbon double bond (C=C). Compounds with double bonds are called alkenes. Alkynes have triple bonds (e.g., ethyne), alcohols have -OH group (e.g., ethanol), alkanes have only single bonds (e.g., ethane). So ethene is an alkene.

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Ethanol is widely used in medicines (tinctures, cough syrups, antiseptics) because it is an excellent solvent. It can dissolve many medicinal compounds that do not dissolve in water. It is also a good antiseptic (kills bacteria). It is not used as a fuel in medicines (though it can burn), not a catalyst (it reacts but does not speed up reactions without being consumed), and not an oxidising agent (it is easily oxidised). So solvent is correct.

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Converting ethanol (C₂H₅OH) to ethanoic acid (CH₃COOH) involves gaining oxygen atoms (or losing hydrogen atoms). This is oxidation. Specifically, ethanol is first oxidised to ethanal (CH₃CHO) and then to ethanoic acid. Displacement is one element replacing another. Neutralisation is acid-base reaction. Reduction is gain of hydrogen or loss of oxygen. So oxidation is correct.

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In a substitution reaction, one atom or group is replaced by another. In the chlorination of methane (CH₄ + Cl₂ → CH₃Cl + HCl), a chlorine atom replaces one hydrogen atom. Chlorine does not replace nitrogen, carbon, or oxygen in typical organic substitution reactions. So hydrogen is correct.

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Sodium ethoxide (C₂H₅ONa) is formed when ethanol reacts with sodium metal: 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑. Sodium carbonate and sodium hydroxide do not react with ethanol to form sodium ethoxide (they are bases but weaker than sodium metal). Sodium chloride does not react with ethanol. So sodium metal is correct.

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Vegetable oils (like sunflower oil, soybean oil, olive oil) contain unsaturated fatty acids — carbon chains with one or more double bonds (C=C). These double bonds make them liquid at room temperature. Saturated carbon chains are found in animal fats (solid at room temperature). Aromatic rings are not typical in oils. So unsaturated carbon chains is correct.

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Methane reacts with chlorine gas in the presence of sunlight (or UV light) to undergo free radical substitution. Sunlight provides energy to break the Cl-Cl bond into chlorine free radicals. The reaction does not require water, a catalyst (though light acts as an initiator), or just heat (though heat can also work, sunlight is the standard condition). So sunlight is correct.

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In chlorination of methane (CH₄ + Cl₂ → CH₃Cl + HCl), one hydrogen atom of methane is replaced (substituted) by a chlorine atom. This is a substitution reaction. It is not neutralisation (acid-base), not oxidation (no gain of oxygen), and not addition (no multiple bond to add across). So substitution reaction is correct.

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When hydrogen is added to an unsaturated hydrocarbon (alkene or alkyne) in the presence of a catalyst (hydrogenation), the double or triple bond becomes a single bond. This produces a saturated hydrocarbon (alkane). For example, ethene (C₂H₄) + H₂ → ethane (C₂H₆). Alkynes become alkenes first, then alkanes. So saturated hydrocarbons is correct.

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Dehydration of ethanol (removal of water) using concentrated sulphuric acid at 443 K produces ethene (C₂H₄). The reaction is: C₂H₅OH → C₂H₄ + H₂O. Ethane would require hydrogenation, ethyne would require further dehydrogenation, methane is a different compound. So ethene is correct.

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A substitution reaction is defined as a reaction in which one atom or group in a molecule is replaced (substituted) by another atom or group. For example, in CH₄ + Cl₂ → CH₃Cl + HCl, H is replaced by Cl. Addition adds atoms across a double/triple bond, oxidation adds oxygen or removes hydrogen, combustion is burning with oxygen. So substitution reaction is correct.

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Ethanol is the common name for ethyl alcohol. It belongs to the alcohol family. It is not an aldehyde (that would be ethanal), not an acid (that would be ethanoic acid), and not a ketone (that would be propanone). So ethanol is also known as alcohol (specifically, grain alcohol).

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Ethyne (acetylene, C₂H₂) mixed with air can be explosive because air contains oxygen but also nitrogen. An uncontrolled explosion is dangerous. For welding, a controlled flame is needed, so a mixture of ethyne with pure oxygen (oxy-acetylene flame) is used, which burns safely and produces very high temperature (about 3300°C). Ethyne-air mixture is avoided because it can explode unpredictably. It does burn, forms water as a product, and produces heat — but the explosion risk is the main reason.

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Animal fats (like butter, lard, tallow) contain mostly saturated fatty acids — carbon chains with no double bonds. This makes them solid at room temperature. Vegetable oils contain unsaturated fatty acids (liquid at room temperature). Animal fats are not alcohols (though they contain glycerol esters), and while they are esters (triglycerides), the main distinguishing feature is saturated fatty acids. So saturated fatty acids is correct.

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Alcohols contain an –OH group that is weakly acidic. They react with reactive metals like sodium, potassium, and magnesium to release hydrogen gas. For example: 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑. This is evolution of hydrogen. They do react with metals (so “no reaction” is wrong). Substitution with sodium is not the correct term (it’s a displacement reaction releasing H₂). Neutralisation with bases does not occur (alcohols are not strong acids). So evolution of hydrogen with metals is correct.

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Hydrogenation is the addition of hydrogen (H₂) across a double or triple bond. For example, ethene + H₂ → ethane. This is an addition reaction because hydrogen is added without removing anything. Oxidation would add oxygen or remove hydrogen. Combustion is burning. Substitution replaces one atom with another. So hydrogenation is an addition reaction.

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Consuming small quantities of dilute ethanol (like in alcoholic beverages) causes intoxication — commonly called drunkenness. Symptoms include loss of coordination, slurred speech, impaired judgement, and euphoria. Sleep can occur with larger amounts, paralysis and death occur only with very high doses (alcohol poisoning). For small quantities, drunkenness is the immediate effect.

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Concentrated sulphuric acid (H₂SO₄) is a strong dehydrating agent. When ethanol is heated with it, water is removed from ethanol to form ethene. The reaction is: C₂H₅OH → C₂H₄ + H₂O. This is dehydration. Neutralisation would be with a base. Oxidation would require an oxidising agent like KMnO₄. Substitution would replace an atom. So dehydration is correct.

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A catalyst is a substance that increases (or sometimes decreases) the rate of a chemical reaction without itself being consumed or chemically changed at the end of the reaction. It does not produce heat (reactions produce heat), it does not permanently slow reactions (it can speed them up), and it is not consumed (it remains unchanged). So changing the rate without being affected is correct.

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The reaction between ethanol and sodium metal produces sodium ethoxide (C₂H₅ONa) and hydrogen gas: 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑. Sodium chloride would require chlorine, sodium hydroxide would be from water reaction, sodium carbonate would require carbon dioxide reaction. So sodium ethoxide is correct.

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Hydrogenation of vegetable oils (adding hydrogen to double bonds) is typically carried out using finely divided nickel (Ni) as a catalyst. Other catalysts like palladium or platinum can also be used, but nickel is the most common and economical. Iron is used in Haber process (ammonia synthesis), zinc and copper are not typical hydrogenation catalysts for oils. So nickel is correct.

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Ethene (C₂H₄) has a carbon-carbon double bond (C=C). It does not have ionic bonds (it is covalent), it does not have only single bonds (that would be ethane), and it does not have a triple bond (that would be ethyne). So double bond is correct.

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Concentrated sulphuric acid (H₂SO₄) is a strong dehydrating agent — it removes water (H₂O) from compounds. For example, it dehydrates ethanol to ethene and sugar to carbon. It can also act as a catalyst in some reactions (like esterification) and as an oxidising agent (when hot and concentrated), but its characteristic role in reactions like dehydration of alcohols is as a dehydrating agent. So dehydrating agent is correct.

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Converting an alcohol (like ethanol) to an alkene (like ethene) involves removing a water molecule (H₂O). This is called dehydration. Reduction would add hydrogen or remove oxygen. Substitution replaces one atom with another. Oxidation would add oxygen or remove hydrogen. So dehydration is correct.

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In a substitution reaction like chlorination of methane, multiple products (CH₃Cl, CH₂Cl₂, CHCl₃, CCl₄) are formed because hydrogen atoms are replaced one by one. Each step replaces one more hydrogen with chlorine. Oxygen presence, reaction speed, or carbon chain breaking are not the reasons. So hydrogen atoms replaced one by one is correct.

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An oxy-acetylene flame (oxygen + ethyne/acetylene) produces a very high temperature of about 3300°C (or higher). This is hot enough to melt most metals, making it ideal for welding and cutting. It does not give low temperature, soot production is undesirable (a proper oxy-acetylene flame is blue and clean), and it burns quickly, not slowly. So very high temperature is correct.

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When ethanol reacts with sodium, sodium displaces hydrogen from the –OH group, forming sodium ethoxide and releasing hydrogen gas. This is a metal displacement reaction (sodium displaces hydrogen). It is not substitution (no replacement of H by Cl etc.), not oxidation (no gain of oxygen), not addition (no multiple bond). For JKBOSE level, metal displacement reaction is the intended answer.

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Ethanol has many commercial uses, but the most well-known are in alcoholic beverages (beer, wine, spirits) and in medicines (as a solvent, antiseptic, and in tinctures). It is also used in perfumes, cosmetics, and as a fuel additive. It is not a major component of explosives (though it can be used in some), not a fertiliser, and not only in paints. So alcoholic drinks and medicines is correct.

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Saturated hydrocarbons (alkanes) are generally fairly unreactive. They have only strong single C–C and C–H bonds with no pi bonds, so they do not easily undergo addition reactions. They do react under certain conditions (combustion, substitution with halogens in sunlight), but compared to alkenes and alkynes, they are relatively inert. They are not ionic, not highly reactive, and not explosive under normal conditions. So fairly unreactive is correct.

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Pure ethanol (100% ethanol, containing no water) is called absolute alcohol. Rectified spirit is about 95% ethanol (5% water). Industrial alcohol is ethanol that has been denatured (made poisonous) for industrial use. Dilute alcohol has a low percentage of ethanol. So pure ethanol is absolute alcohol.

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Ethanol is miscible with water in all proportions (completely soluble). This is because ethanol can form hydrogen bonds with water molecules due to its –OH group. It does not matter if the water is hot or cold — ethanol dissolves easily. So “in all proportions” is correct. Methanol and propanol are also soluble, but higher alcohols become less soluble.

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Absolute alcohol (pure 100% ethanol) is highly toxic. Even a small quantity can cause severe alcohol poisoning, leading to respiratory failure, coma, and death. It is much more dangerous than dilute alcoholic beverages. It is not safe, not beneficial (though very dilute ethanol in medicines is used externally), and not neutral. Even a small amount can be lethal. So lethal is correctClose