Final Chemistry Quiz - 2019 Batch

Van der Waals forces are intermolecular forces that exist between all molecules, regardless of whether they are saturated or unsaturated compounds. These forces arise due to temporary fluctuations in electron distribution, causing temporary dipoles. Therefore, Van der Waals forces do not determine where the H atom should be placed in unsaturated compounds.

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The configuration around carbons labeled 1 and 2 is (R, R) because both carbons have the same substituents in a clockwise direction. According to the Cahn-Ingold-Prelog priority rules, the higher priority groups are on the same side, resulting in an (R) configuration for both carbons.

The angle of rotation for the mirror image of a compound is equal to the negative of the original angle of rotation. Therefore, if the angle of rotation for the compound is +12, the angle of rotation for its mirror image would be -12.

The geometry around the central atom in the molecular model of PH3 is pyramidal. This is because phosphorus (P) has three bonded hydrogen (H) atoms and one lone pair of electrons, resulting in a trigonal pyramidal shape. The lone pair pushes the bonded atoms away from it, causing the molecule to adopt a pyramidal shape.

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The answer suggests that compound 2 is the most stable, followed by compound 3, compound 1, and finally compound 4. Stability of compounds is often determined by factors such as bond strength, resonance, and electron distribution. Without further information, it is difficult to provide a detailed explanation for the given order of stability.

LiAlH4 is a strong reducing agent that can be used to reduce aldehydes to alcohols. When LiAlH4 is added to an aldehyde, it donates a hydride ion (H-) to the carbonyl carbon, resulting in the formation of an alkoxide intermediate. This intermediate is then protonated by H3O+ to yield the corresponding alcohol. The other reagents listed, BH3/H2O2, KMnO4, and NH2NH2/OH-, do not have the ability to directly reduce aldehydes to alcohols.

N,N-Dimethylacetamide is the correct answer because it is the organic product obtained from the reaction of dimethylamine with acetic acid. This is a condensation reaction where the amine group of dimethylamine reacts with the carboxylic acid group of acetic acid to form an amide bond. The resulting compound is N,N-Dimethylacetamide, which is a commonly used solvent in various chemical reactions and industrial processes.

The given question is asking about the result of a reaction involving 2-Iodo-2-butanol and 3-Iodo-2-butanol. The correct answer is "No reaction will happen." This means that when these two compounds are mixed together, no chemical reaction will occur between them.

The boiling point of a compound is determined by its intermolecular forces. The compound with the strongest intermolecular forces will have the highest boiling point. In this case, compound 4 has the strongest intermolecular forces, followed by compound 2, compound 1, compound 3, compound 6, and finally compound 5. Therefore, the correct order of increasing boiling point is 4>2>1>3>6>5.

2-hexene can exist as cis-trans isomers because it contains a carbon-carbon double bond, which allows for rotation around the bond. In the cis isomer, the two substituents on the same side of the double bond, while in the trans isomer, the two substituents are on opposite sides of the double bond. The other compounds listed do not have a carbon-carbon double bond and therefore cannot exhibit cis-trans isomerism.

This compound does not have any stereogenic carbon because stereogenic carbons are carbon atoms that have four different groups attached to them, resulting in the possibility of having two different stereoisomers. Since this compound does not have any such carbon atoms, the answer is zero.

When a primary alcohol is treated with H2CrO4, it undergoes oxidation. H2CrO4 is a strong oxidizing agent that converts primary alcohols to carboxylic acids. Therefore, the correct answer is carboxylic acid.

The question asks for personal preference among the given options. The correct answer is A, indicating that the person likes option A the most out of all the options provided.

2,2-dimethyl-1-propanol undergoes oxidation when treated with K2Cr2O7 / H2SO4 to yield a carboxylic acid. This is because the presence of the oxidizing agent (K2Cr2O7) and the acidic medium (H2SO4) promotes the oxidation of the alcohol functional group to a carboxylic acid functional group. The other options, 2-methyl-2-propanol, phenol, and cyclohexanol, do not have the necessary functional groups or conditions to undergo this oxidation reaction.

The compound 2-phenyl-2-butanol is named according to the IUPAC nomenclature system. It is a secondary alcohol with a phenyl group attached to the second carbon of the butanol chain. The prefix "2-phenyl" indicates the position of the phenyl group, while "2-butanol" indicates the position of the hydroxyl group. The suffix "-ol" indicates that it is an alcohol.

Thiophenol is more acidic than thiol because the presence of the sulfur atom in thiophenol stabilizes the negative charge on the conjugate base, making it easier to donate a proton. In contrast, thiols do not have this stabilizing effect, so they are less acidic.

When the Ka increases, it means that the acid dissociates more readily in water, resulting in a higher concentration of hydronium ions (H3O+). A higher concentration of hydronium ions indicates a stronger acid, which leads to a lower pKa value. Therefore, the statement "When the Ka increases, the pKa decreases" is correct. Similarly, when the pOH decreases, it means that the concentration of hydroxide ions (OH-) decreases, indicating a higher concentration of hydronium ions. This suggests a stronger base, leading to an increase in basicity. Hence, the statement "When the pOH decreases, the basicity increases" is also correct.

A carboxylic acid is a stronger acid than ethanol because upon ionization, the carboxylate ion is stabilized by resonance.

The correct name for the compound is 1-ethyl-3-fluoro-5-isopropylbenzene because it follows the IUPAC naming rules for organic compounds. The numbers indicate the positions of the substituents on the benzene ring, and the substituents are listed alphabetically. In this case, the ethyl group is at position 1, the fluoro group is at position 3, and the isopropyl group is at position 5.

The given molecule consists of a benzene ring with a substituent at the 5th carbon and a carbonyl group at the 3rd carbon. The substituent at the 5th carbon is an ethyl group (-CH2CH3) and the carbonyl group at the 3rd carbon is an aldehyde (-CHO). Therefore, the correct IUPAC name for this molecule is 5-ethyl-3-oxobenzaldehyde.

Hexanal undergoes nucleophilic addition reaction because it contains a carbonyl group (C=O), which is a strong electrophile. In nucleophilic addition reactions, a nucleophile attacks the electrophilic carbon of the carbonyl group, resulting in the addition of the nucleophile and the formation of a new bond. In the case of hexanal, the carbonyl carbon is susceptible to attack by nucleophiles, making it capable of undergoing nucleophilic addition reactions.

PCC (pyridinium chlorochromate) in CH2Cl2 is the most suitable reaction to convert 2-hexanol to 2-hexanone. PCC is a mild oxidizing agent that selectively converts primary alcohols to aldehydes or ketones. In this case, 2-hexanol is a primary alcohol, and PCC will oxidize it to form 2-hexanone. CH2Cl2 is the solvent used for the reaction.

When a solute is added to a solvent to form a solution, the freezing point of the solution decreases compared to the freezing point of the pure solvent. This is because the presence of the solute disrupts the arrangement of the solvent molecules, making it more difficult for them to form a solid lattice and freeze. As a result, a lower temperature is required to freeze the solution compared to the pure solvent.

The correct answer is to react Thiol + base, then with 1° Alkyl halide. This is because the process of preparing Sulfide involves the reaction of Thiol (a compound containing a sulfur-hydrogen bond) with a base to form the corresponding thiolate ion. The thiolate ion then reacts with a 1° Alkyl halide (a compound containing a halogen atom bonded to a carbon atom) through a substitution reaction, resulting in the formation of the desired Sulfide compound.

The compound in question is a nonene, which means it has nine carbon atoms. The "trans" or "cis" prefix indicates the arrangement of substituents on the double bond. In this case, the substituents are the methyl and isopropyl groups. The "trans" prefix indicates that the substituents are on opposite sides of the double bond, while the "cis" prefix indicates that they are on the same side. The correct answer is "Trans-6-isopropyl-7,8-dimethyl-3-nonene" because it accurately describes the arrangement of the substituents on the double bond and the position of the methyl and isopropyl groups on the carbon chain.

The correct answer is amide. An amide is a functional group that consists of a carbonyl group (C=O) bonded to a nitrogen atom (N). In the given compound, there is a carbonyl group bonded to a nitrogen atom, indicating the presence of an amide functional group. The other options mentioned (amine, ether, amine carbonyl) are not applicable to the compound as they do not accurately represent the functional groups present.

The given compound has a chlorine atom attached to the fourth carbon atom, two methyl groups attached to the second carbon atom, and an aldehyde group attached to the fifth carbon atom. Therefore, the correct IUPAC name for this compound is 4-chloro-2,2-dimethyl-5-hexenal.

The compound CH2(OH)CH3 is the correct answer because it reacts with Jones reagent and changes the color to green. Additionally, when it reacts with KMnO4, it yields CH3COOH, which is acetic acid. This indicates that the compound has a hydroxyl group (OH) and a methyl group (CH3), which matches the structure of CH2(OH)CH3, also known as 2-propanol.

The priority order is determined by the functional groups present in each compound. The highest priority is given to the -OH group because it is an alcohol, which is a very reactive functional group. Next in priority is -CCL4, which is a haloalkane and also reactive. -CH (CH3)2 is next because it is a tertiary alkyl group, followed by -CH2NH2, which is an amine. Lastly, -CH3 is given the lowest priority because it is a simple alkyl group.

The correct answer is Thiols. Thiols are responsible for the strong and unpleasant odor we perceive when we cut garlic. Thiols are organic compounds that contain a sulfur atom bonded to a hydrogen atom. In garlic, the presence of sulfur compounds, including thiols, is what gives it its distinctive smell. When garlic is cut or crushed, enzymes in the garlic react with these sulfur compounds, releasing volatile molecules that are responsible for the characteristic odor.

Alkanes are hydrocarbons consisting of only carbon and hydrogen atoms bonded together. They are known for being less dense than water. This is because the carbon-hydrogen bonds in alkanes are nonpolar, resulting in a relatively low intermolecular force between molecules. As a result, alkanes tend to have lower densities than water, causing them to float on top of water.

The IUPAC name of the given compound is -propyl-4-heptyn-1-ol. This name indicates that the compound contains a propyl group (-propyl) attached to the fourth carbon atom (4-) of a heptyne chain. It also has a hydroxyl group (-ol) attached to the first carbon atom (1-) of the heptyne chain.

In the drawing of acetic acid CH3CO2H, a partial positive charge occurs on the carbon atom (C) and the oxygen atom (O) in the carboxyl group (COOH). The carbon atom in the carboxyl group is electron-deficient due to the presence of the highly electronegative oxygen atom, causing it to have a partial positive charge. Similarly, the oxygen atom in the carboxyl group also has a partial positive charge due to the electron-withdrawing effect of the adjacent carbon atom. Therefore, the correct answer is (b) and (d).

The correct answer is propanal+2(2-methylpropanol) because it provides the necessary reactants to yield the desired compound. Propanal is the aldehyde needed to form the compound, and 2(2-methylpropanol) is an alcohol that can undergo a condensation reaction with propanal to form the desired compound. The other options do not provide the correct combination of reactants.

The correct arrangement of the compounds according to their basicity strength is NaH>NaOH>NO3-. This means that NaH is the strongest base, followed by NaOH, and then NO3-. This is because NaH is a strong base due to its ability to donate hydroxide ions (OH-) easily, while NaOH is a weaker base because it is a salt of a strong base and a weak acid. NO3- is the weakest base as it is the conjugate base of a strong acid (HNO3).

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Ethyl cyclohexane has the least melting point compared to the other compounds listed. This is because ethyl cyclohexane is a smaller molecule with less branching and fewer carbon atoms compared to the other compounds. Smaller molecules tend to have weaker intermolecular forces, such as London dispersion forces, which are easier to overcome, resulting in a lower melting point. The other compounds, such as octane, 2,2-dimethyl heptane, and nonane, have larger and more complex structures with more carbon atoms and more branching, leading to stronger intermolecular forces and higher melting points.

Molality is a relationship that connects the moles of solute with the mass of solvent. It is a concentration unit that is expressed as the number of moles of solute per kilogram of solvent. This relationship is important in determining the concentration of a solution, as it takes into account the mass of the solvent rather than its volume. By considering the mass of the solvent, molality allows for more accurate calculations and comparisons between different solutions.

The O-S-O bond angle in SO3 is 120 degrees. This is because SO3 has a trigonal planar molecular geometry, where the three oxygen atoms are arranged in a flat triangle around the central sulfur atom. In a trigonal planar geometry, the bond angles between the atoms are all equal and are 120 degrees.

H3PO4 is the strongest ionization among the given options. This is because it is a triprotic acid, meaning it can donate three protons (H+) in solution. The other options, PO4-3, HPO4-2, and H2PO4-, are all conjugate bases of H3PO4 and have fewer protons to donate. Therefore, H3PO4 has the highest ionization strength.

The given molecule is named as 2-Bromo-5-ethyl-6-methyl-3-heptyne. This name accurately describes the structure of the molecule, indicating the positions and types of substituents on the carbon chain. The prefix "2-Bromo" indicates that there is a bromine atom attached to the second carbon atom in the chain. The prefixes "5-ethyl" and "6-methyl" indicate that there are ethyl and methyl groups attached to the fifth and sixth carbon atoms, respectively. The suffix "-yne" indicates that the molecule contains a triple bond between the third and fourth carbon atoms.

In the reaction of acids with nitrogen-containing compounds, the result is not water and salt, salt and CO2, or water and CO2. The reaction between acids and nitrogen-containing compounds can result in various products depending on the specific compounds involved. It could lead to the formation of ammonium salts, nitric acid, or other nitrogen-containing compounds. Therefore, none of the given options accurately describe the result of this reaction.

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The given answer suggests that compound 1 is the most reactive, followed by compound 3, 5, 2, and 4 in increasing order of reactivity.

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The organic compound must be an aldehyde. Jones reagent is a solution of chromic acid in sulfuric acid, which is commonly used to oxidize aldehydes to carboxylic acids. The green color change indicates the presence of an aldehyde. 2,4-dinitrohydrazine is a reagent used to test for the presence of carbonyl compounds, specifically aldehydes and ketones. The formation of an orange precipitate indicates that the unknown compound is an aldehyde. Therefore, the correct answer is Option 4.