GAT Test - 10

Explanation:

When an electric current passes through a conducting solution, it causes a series of interesting and observable effects due to the interaction between electricity and the solution’s constituents. These phenomena occur as a result of the electrolytic process, where ions in the solution move towards the electrodes, causing chemical reactions. The possible effects include:

• Heating of the Solution: As electric current flows through the solution, it encounters resistance which generates heat. This can raise the temperature of the solution, leading in some cases to evaporation depending on the solution’s boiling point and the amount of current applied.
• Formation of Gases at Electrodes: Electrochemical reactions at the electrodes can lead to the production of gases. For example, electrolysis of water produces hydrogen and oxygen gases at the cathode and anode respectively. These gases may be observed as bubbles forming at the electrodes.
• Change in Color of the Solution: The chemical reactions occurring in the solution can also lead to changes in color. This is particularly noticeable in solutions containing metal ions that undergo oxidation or reduction, altering their charge and subsequently, their color representation in solution.

Concepts:

1. Electrolysis: The process by which ionic substances are decomposed into simpler substances when an electric current is passed through them.
2. Electrochemical Reactions: Chemical reactions that take place at the interface of an electron conductor (the electrode) and an ionic conductor (the electrolyte) which involve electron transfer between the electrode and the electrolyte or species in solution.
3. Oxidation and Reduction: Reactions in which one species loses electrons (oxidation) and another gains electrons (reduction). These are often coupled in electrochemical reactions.
4. Thermal Effects of Electric Current: The phenomenon where electric current passing through a medium generates heat due to the medium's resistance to the current’s flow.

Conclusion:

So, the possible effects when an electric current passes through a conducting solution are all of the above-mentioned in options.

The correct answer is Aspirin.

Concept:

• A carboxylic acid is a functional group in which the carbon atoms bonded to the oxygen atom by a double bond. 
• The hydroxyl group -OH is bounded by a single bond. 
• The fourth bond is attached to an alkyl or an aryl group.

Explanation:

• Aspirin is also known as acetylsalicylic acid.
• Aspirin is a weak acid.
• It is a salicylic acid derivative in which the hydroxyl group of salicylic acid is acetylated. 
• It contains three groups:
  • The carboxylic acid functional group (R-COOH)
  • Ester functional group (R-O-CO-R')
  • Aromatic group (benzene ring)​

Structure of Aspirin

Thus, the carboxylic functional group (−COOH) is present in Aspirin.

Additional Information

Picric acid

• Picric acid is a derivative of phenol.
• Picric acid is a weak acid due to the presence of the hydroxyl group on it.
• The structure of picric acid is as shown below,

Thus, it does not contain the carboxylic functional group (−COOH).

Barbituric acid

• Barbituric acid is acid.
• It contains the carbonyl group and the -NH group.
• The structure of barbituric acid is as shown below,

Thus, it does not contain the carboxylic functional group (−COOH).

Ascorbic acid

• Ascorbic acid is also found to be acidic.
• The structure of ascorbic acid is as shown below,

Thus, it does not contain the carboxylic functional group (−COOH).

The correct answer is (a), (b) and (c)

Concept:-

• Chemical Reactions: Understanding that rusting is a chemical process where reactants (iron and oxygen) form a product (iron oxide).
• Thermodynamics: Recognizing rusting as an exothermic reaction, one that releases energy, highlights the importance of energy considerations in chemical reactions.
• Environmental Conditions: Knowing that certain reactions, like rusting, can happen under specific environmental conditions, such as the availability of water and suitable temperature.
• Reversibility of Reactions: Identifying whether a chemical reaction is reversible or not is key to understanding the permanence of the reaction's products and the feasibility of recovering the reactants.

Explanation:-

Rusting is a common chemical reaction where iron reacts with oxygen in the presence of water or moisture. This process leads to the formation of iron oxide (rust).

Nature of the Reaction (a): The statement that rusting involves a chemical reaction between iron and oxygen is true. The presence of water acts as a catalyst, accelerating the process. The chemical equation for rusting can be simplified as:

(4Fe + 3O₂ + 6H₂O→ 4Fe(OH)₃),
which upon dehydrating gives iron oxide, or rust.

Exothermic Reaction (b): Rusting is an exothermic reaction. Although the amount of heat released during the reaction is relatively low, it indeed releases energy to the surrounding environment, confirming that it is exothermic.

Room Temperature Reaction (c): Rusting can, and commonly does, occur at room temperature. The presence of moisture (water) and oxygen in the air at room temperature is sufficient to initiate and sustain the rusting process.

Reversibility (d): Rusting is not a reversible reaction under normal conditions. Once iron has oxidized to form rust, converting it back to pure iron requires a chemical process that involves reduction, typically not occurring spontaneously in nature.

Conclusion:-

The statements (a) It involves a chemical reaction between iron and oxygen, (b) It is an exothermic reaction, and (c) It can take place at room temperature, are all true regarding the rusting of iron.

The statement (d) It is a reversible reaction, is false since rusting does not easily reverse back to iron and oxygen under normal conditions.

Therefore, the correct answer is  (a), (b) and (c)

The correct answer is Metals, non-metals, reduction

Explanation:

• Metals are elements that are typically shiny, ductile, and conduct heat and electricity well. Examples include iron, copper, and gold.
• Non-metals are elements that are often dull, brittle, and poor conductors of heat and electricity. Examples include sulfur, carbon, and oxygen.
• Reduction is a process in which a metal gains electrons, reducing its oxidation state. This process is a part of redox (reduction-oxidation) reactions.

 Key Points

• Metals: Known for their shiny appearance (luster), malleability, ductility, and excellent conductivity. They are often used in electrical wiring, construction, and manufacturing.
• Non-metals: Characterized by their lack of luster, brittleness, and poor conductivity. They are critical in various chemical reactions and are found in many compounds essential to life.
• Reduction: Involves the gain of electrons by an atom or ion, leading to a decrease in its oxidation state. It is the opposite of oxidation, where an atom or ion loses electrons.

Metals are typically shiny and conductive, non-metals are often dull and brittle, and reduction is the process where a metal gains electrons and decreases its oxidation state.

The correct answer is butane > cyclohexane > pentane > hexane.

Key Points

To determine the correct order of octane numbers among butane, pentane, hexane, and cyclohexane, let's consider the general properties and typical octane ratings for each:

• Butane (n-butane) - Typically, butane has a relatively high octane rating. For instance, n-butane has an octane rating of around 94 (Research Octane Number, RON).
• Pentane (n-pentane) - Pentane usually has a lower octane rating compared to butane. n-Pentane, for example, has an octane rating of around 62.
• Hexane (n-hexane) - Hexane's octane rating is generally lower than that of pentane, with n-hexane typically around 25.
• Cyclohexane - Cyclohexane tends to have a lower octane rating than the other listed alkanes. It's typically used as a reference with a very low octane rating, around 82.

Given this information, the correct order of octane numbers from highest to lowest among these compounds is:

• Butane (highest)
• Cyclohexane
• Pentane
• Hexane (lowest)

Thus, the correct answer, based on the typical octane ratings, would be: 3) butane > cyclohexane > pentane > hexane

Additional Information

• The concept of octane rating was developed by chemist Russell Marker in the 1920s. The octane number is a measure of a fuel's ability to resist "knocking" or "pinging" during combustion, caused by the air/fuel mixture detonating prematurely in the engine.
• In the context of engine performance, fuels with higher octane numbers are preferred for high-performance engines to prevent knocking, which can lead to engine damage over time.
• The octane rating of a fuel can be increased by refining processes such as isomerization, which increases the proportion of branched-chain hydrocarbons, or by adding anti-knock agents like lead tetraethyl (although its use has been greatly reduced for environmental reasons).

The correct answer is Al₂O₃.

Key Points

Amphoteric Oxides

• Amphoteric oxides are oxides that can act as both acids and bases. They can react with both acids and bases to produce salts and water.
• Aluminum oxide (Al₂O₃) is a classic example of an amphoteric oxide. It reacts with acids to form aluminum salts and water and with bases to form salts and water as well.
• For example, when Al₂O₃ reacts with hydrochloric acid (HCl), it forms aluminum chloride (AlCl₃) and water. When it reacts with sodium hydroxide (NaOH), it can form sodium aluminate (NaAlO₂) and water.
• This dual behavior is due to the electronic structure of the aluminum ion, which allows it to form covalent bonds with oxygen in acidic and basic environments.
• Magnesium oxide (MgO) and sodium oxide (Na₂O) are primarily basic oxides, while P₄O₁₀ is an acidic oxide, not demonstrate amphoteric properties.

Hence, the correct option is Al₂O₃.

Additional Information

• Basic oxides: These are oxides that react with acids to form salt and water. Examples include CaO (calcium oxide), which reacts with HCl to form calcium chloride and water.
• Acidic oxides: Oxides that react with bases to form salts and water. An example is SO₃ (sulfur trioxide), which reacts with NaOH to form sodium sulfate and water.
• Applications of Al₂O₃: Aluminum oxide has wide applications due to its physical and chemical properties. It is used as an abrasive in sandpapers, as a refractory material due to its high melting point, and in the production of aluminum metal.

The correct answer is Hybridization.

Key Points

• Hybridization in organic compounds is a concept that explains the bonding and structure of molecules.
• It involves the mixing of atomic orbitals to form new hybrid orbitals, which can form sigma bonds and pi bonds in the molecules.
• The type of hybridization affects the bond length and bond angles in the molecule.
• For example, in sp³ hybridization, the bond angles are approximately 109.5° and the bond lengths are typically longer than those in sp² and sp hybridizations.
• In sp² hybridization, the bond angles are approximately 120°, and in sp hybridization, they are 180°.
• The bond length decreases as the s-character of the hybrid orbitals increases (sp > sp² > sp³).

Additional Information

• Bond Length
  • The bond length is the distance between the nuclei of two bonded atoms.
  • It depends on the types of atoms and the type of bond (single, double, triple).
  • Single bonds are generally longer than double bonds, which are longer than triple bonds.
• Heating Capability
  • The heating capability or thermal stability of a bond is influenced by the bond strength.
  • Triple bonds are generally stronger and more thermally stable than double and single bonds.
  • The hybridization state of the atoms involved can affect the overall stability of the molecule under heat.

The percentage of carbon in CO₂ is 27.3.

To obtain the percentage of any element in a compound, firstly we need to take the individual atomic mass of the element and divide it by the total molecular mass of both the compounds.

Mass of carbon=12

Mass of oxygen = 16 as there are 2 oxygen (16 x 2 = 32)

12/32 + 12 = 0.2727

0.2727 x 100 = 27.21%

Hence, the percentage of carbon in CO₂ is approximately 27.3.

The correct answer is Tetrachloroethylene.

Key Points

• Tetrachloroethylene is the chemical commonly used in waterless washing, also known as dry cleaning.
• Dry cleaning is a process of cleaning clothes and fabrics using a solvent other than water, such as tetrachloroethylene, to remove stains and dirt.
• Tetrachloroethylene, also known as perchloroethylene or "perc," is a chlorinated solvent that is effective in dissolving oils, greases, and other organic compounds from fabrics.

Additional Information

• Sodium bicarbonate:
  • Sodium bicarbonate, also known as baking soda, is a mild alkali commonly used in household cleaning and as a leavening agent in baking.
• Hydrogen peroxide:
  • Hydrogen peroxide is a mild bleaching agent and disinfectant commonly used for household cleaning and as a topical antiseptic.
  • While it may be used in some cleaning processes, it is not the primary chemical used in waterless washing or dry cleaning.
• Acetic acid:
  • Acetic acid, commonly known as vinegar, is a weak acid often used in household cleaning and as a food preservative.
  • It is not typically used as the primary solvent in dry cleaning processes.

The correct answer is i-b, ii-c, iii-d, iv-a.

Key Points

• Pepsin is a proteolytic enzyme that digests the proteins present in the stomach.
• Proenzyme pepsinogen is secreted in the stomach and gets converted to pepsin in the presence of hydrochloric acid in the stomach.
• Dietary proteins that reach the stomach get digested by pepsin.
• Pepsin is most efficient in cleaving peptide bonds between hydrophobic and preferably aromatic amino acids such as phenylalanine, tryptophan, and tyrosine.
• Carbohydrate digestion also initiates in the mouth. Amylase, produced by the salivary glands, breaks complex carbohydrates, mainly cooked starch, to smaller chains, or even simple sugars. It is sometimes referred to as ptyalin.
• Alkaline phosphatase (ALP) is an enzyme that's found throughout your body. An enzyme is a type of protein in a cell that acts as a catalyst and allows certain bodily processes to happen. Most ALP is found in your liver, bones, and kidneys.
• Maltase: converts maltose into glucose. It is present in the small intestine.