Organic Chemistry MCQs

Ans: (C ) C₆H₁₂O₆

Explanation:

1 gramme of hydrogen = 0.0833-mole carbohydrate

As a result, 1 mole of carbohydrate equals (1/0.0833) = 12g of hydrogen.

Hydrogen Equals 2g in the empirical formula (CH₂O).

As a result, n = (12)/(2) = 6

As a result, carbohydrate has the chemical formula =(CH₂O)₆ = C₆H₁₂O₆.

Ans: (D) Electromeric effect

Explanation: The electromeric effect is a transient effect that is activated when an attacking reagent is required. An intramolecular electron displacement causes the electromeric effect, which is a molecular polarizability effect. It's a one-time effect.

When the attacking reagent is a nucleophile and the pi electrons are transported to an atom that the attacking reagent will not bond with, the -E effect occurs. The addition of nucleophiles to carbonyl compounds is an example of the -E effect at work.

Ans: (B) Meso compound

Explanation: Plane polarised light is not rotated by the Meso compound. A Meso compound is a molecule that contains tetrahedral atoms with four distinct groups yet is chiral throughout. It is optically inactive and has a plane of symmetry. One of the asymmetric carbon atoms rotates the plane of polarised light to the right, while the other rotates it to the left, to the same extent, such that the rotation caused by the upper half is compensated by the bottom half, resulting in no rotation of the plane polarised light.

Ans: (C ) Halogen

Explanation: The Carius method is used to calculate halogens. In this process, the compound is first heated in the presence of nitric acid and silver nitrate, which transforms any halogens or sulphur present into their equivalent silver salt. The amount of halogen or sulphur in the silver salt can then be determined based on the amount of silver salt recovered.

Ans: (B) Different molecular weight

Explanation: If two compounds have the same empirical formula or percentage composition, then whatever elements are present in both compounds have the same per cent element composition, but both compounds have different molecular formulas or molecular weights. CH2O and C6H12O6, for example, have the same empirical formula but a distinct molecular formula, and their molecular weights are different.

Ans: (B) Bakelite

Explanation: Bakelite is a thermosetting polymer. A thermosetting polymer can be irrevocably hardened to get the required shape. The process of curing a soft solid or viscous liquid prepolymer or resin hardens it. Curing is caused by heat or appropriate radiation, and it can be accelerated by applying high pressure or mixing with a catalyst. A thermoset cannot be reshaped after it has hardened.

Ans: (A) Friedrich Wohler

Explanation: Frederich Wohler is the father of organic chemistry, he was a chemist responsible for the isolation of pure aluminium. Many chemists regard him as the founder of organic chemistry since he demonstrated that a nonliving mineral (ammonium cyanate) could be converted into a chemical found in living organisms (urea from urine).

Ans: (A) Propane

Explanation: Propane is utilised as a light source. Propane has the chemical formula C3H8, and it is a liquid natural gas that is commonly used for cooking as Liquefied petroleum gas (LPG). It is kept as a colourless, odourless liquid under pressure in a tank. When the pressure is released, the liquid propane vaporises and transforms into a gas that can be burned.

Ans: (B) Carbon monoxide

Explanation: When exhaled, carbon monoxide from incomplete combustion is detrimental because it displaces oxygen in the bloodstream, denying oxygen to the heart, brain, and other important organs. CO poisoning can strike without notice, causing you to lose consciousness and suffocate in minutes.

Ans: (C ) Ethane

Explanation: Saturated hydrocarbons are hydrocarbons that only have single carbon atom bonds. They are the most basic type of hydrocarbon. Because each carbon atom is connected to as many hydrogen atoms as possible, they are said to as saturated. To put it another way, the carbon atoms are hydrogen-saturated. Ethane is one of saturated hydrocarbon with a formula C2H6

Ans: (D) Nitrogen

Explanation: Amines are carbon-nitrogen linkages containing compounds. In an amine, the nitrogen atom possesses a single pair of electrons and three links to other atoms, all of which are carbon or hydrogen. A variety of nomenclatures are used to name amines, but they all contain the class-identifying suffix -ine. Some of the examples are Methyl Amine, Pyridine.

Ans: (D) PMMA Poly-Methyl-Meth-Acrylate

Explanation: PMMA (polymethylmethacrylate) is a synthetic adhesive made from the polymerization of methyl methacrylate. PMMA is a translucent and rigid plastic that is frequently used as a glass substitute in goods such as shatterproof windows, skylights, illuminated signs, and plane canopies.

Lexan is a polycarbonate, which is a thermosetting polymer with carbonate groups. They have a hard surface and are visibly transparent. Bulletproof glass is made from laminated polycarbonate (Lexan) for this purpose.

Ans: (B) Amino acids

Explanation: The main structure of a protein is defined as the linear sequence of amino acids within it. Proteins are made up of a small number of amino acids, each with its side chain. Nonpolar side chains make up the majority of amino acids, and they have a wide range of chemistries.

Ans: (B) Sucralose

Explanation: Sucralose has been chemically altered to be 600 times sweeter than sugar while containing nearly no calories. Sucralose is utilised in foods like yoghurt, confectionery, ice cream, and soda since it doesn't leave an aftertaste on your tongue. It was the first artificial sweetener to be used by diabetics.

Ans: (A) Methane

Explanation: Methane, hydrogen sulphide and carbon dioxide are the main components of biogas, which is also known as marsh gas. As a result, methane is now referred to as marsh gas. Marsh gas is primarily composed of methane, with minor amounts of other gases present. With one carbon atom and four hydrogen atoms, methane is the lightest hydrocarbon. It has a molecular mass of 16.

Ans: (D) 146

Explanation: Subtracting the atomic number from the atomic mass yields the number of neutrons in an atom. On the periodic table, both of these numbers can be found. The atomic number appears above the element's symbol, while the mass number appears below.

The atomic number of Uranium is 92 and the atomic mass is 238

The number of Neutrons is equal to 238-92=146.

Ans: (A) High Elongation

Explanation: A tension test determines elongation, which is a measure of a material's ductility. It's the difference between a test specimen's original gauge length and the increase in gauge length following a fracture. Greater elongation equals greater ductility.

Polymers are large molecules with a great deal of elongation. They're vital compounds that can be found in our bodies as proteins and nucleic acids, in plants as starch and cellulose, and our daily lives as fibres, plastics, and elastomers.

Ans: (D) Photosynthesis

Explanation: The process of constructing a bigger molecule by combining smaller ones. An example of an anabolic reaction is photosynthesis. It creates sugars by combining smaller molecules such as carbon dioxide and water in the presence of sunlight, yielding oxygen and glucose as well as some energy.

Ans: (B) Maltose

Explanation: A disaccharide is maltose. Maltose, often called maltobiose or malt sugar, is a disaccharide made up of two glucose units. 

Galactose is a monosaccharide sugar that is similar to glucose in sweetness. It's a glucose C-4 epimer.

Glucose is a monosaccharide hydrocarbon polymer and a carbohydrate monomer.

Fructose, often known as fruit sugar, is a ketonic monosaccharide present in a variety of plants.

Ans: (A) C₂H₂

Explanation: The chemical compound acetylene, often known as ethyne, has the formula C₂H₂. It is the simplest alkyne and a hydrocarbon. This colourless gas is employed as a fuel and a chemical building ingredient in a variety of applications. It is normally treated as a solution because it is unstable in its pure state.

Ans: (B) C₃H₄

Explanation: Alkynes are carbon-based molecules with a triple bond between carbon atoms. Propyne is a three-carbon-atom chemical with the general formula of an alkyne.

C₃H₄ belongs to the alkyne family since it matches the generic formula CNHCN-2 for a compound with n = 3.

Ans: (B) Anhydrous ZnCl2/HCL

Explanation: A solution of anhydrous zinc chloride in concentrated hydrochloric acid is used in the Lucas test to identify and categorise primary, secondary, and tertiary alcohols. The Lucas reagent is the name given to this solution. The reactivity of primary, secondary, and tertiary alcohols with the Lucas reagent is used to classify them. The Lucas test's reaction can be thought of as a nucleophilic substitution reaction. The Chloride in the zinc-chloride bond is replaced with a hydroxyl group derived from the supplied alcohol in this process.

Ans: (D) Covalent bond

Explanation: Organic compounds have tetravalent carbon atoms in particular. This is due to their proclivity for transferring electrons. A covalent bond is created between two electronegative atoms, such as carbon, which is electronegative. A covalent link is produced between two carbon-carbon atoms.

Covalent bonds are the strongest bonds in nature, and they must be broken with the help of enzymes under normal biological conditions. This is because the connected atoms distribute electrons evenly, and since everything is equally shared, there is no conflict to weaken the arrangement.