Chemistry: CUET Mock Test - 6 - CUET MCQ

Drugs that either prevent the enzyme from holding the substrate or prevent it from providing functional groups that attack the substrate, are called enzyme inhibitors. These inhibit the catalytic activity of enzymes.

S_N2 reaction proceeds with stereo chemical inversion.

The process of conversion of enantiomer into Racemic mixture is known as Racemisation. A mixture containing 2 enantiomers in equal proportions is known as Racemic mixture.

The stereoisomers related to each other as superimposable mirror image are identical with each other.

The object which are non-superimposable on their mirror image are said to be chiral and this property to known as chirality.

So, only A, C & E are correct statement.

The neopentyl group has four carbons, and all the carbons are bonded to a hydrogen atom except for one, which is bonded to a chlorine atom. The neopentyl group is attached to a propane chain, which has three carbons.

To name this compound using IUPAC nomenclature, we follow the following steps:

Identify the longest carbon chain: In this case, it is a propane chain with three carbons.

Number the carbon chain: We start numbering from the end nearest to the substituent, which is the neopentyl group. The carbon atom in the neopentyl group that is attached to the chlorine atom is assigned the lowest possible number. Therefore, it is numbered as carbon 1.

Identify and name the substituents: The neopentyl group is a substituent in this compound. The substituent name is derived from the name of the parent hydrocarbon, neopentane. The neopentyl group has four carbon atoms, so its prefix is "neo-".

Assign locants to the substituents: The substituent is attached to carbon 2 of the propane chain. Therefore, it is named as 2-neopentyl.

Name the functional group: The functional group in this compound is a halogen (chlorine) and is named as chloro.

Complete the name: Putting it all together, we get the IUPAC name of neopentyl chloride as 1-chloro-2,2-dimethylpropane.

1-chloro-2, 2-dimethylpropane

sp³ hybridized carbon atom show fast nucleophilic substitution reaction than sp² hybridized carbon atom.

• The boiling points of alcohols increase with increase in the number of carbon atoms (increase in van der Waals forces). In alcohols, the boiling points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area)
• Boiling point of alcohols is more in comparison to hydrocarbons of comparable molecular mass due to intermolecular hydrogen bonding.
• Boiling point of alcohols are higher in comparison to other classes of compounds, namely hydrocarbons, ether, haloalkanes and haloarenes of comparable molecular masses.

Note : In statement E, we have to consider inter molecular hydrogen bonding instead of intramolecular hydrogen bonding.

More electron withdrawing group attached with alcohols or phenols, more will be the acidity

​Alkyl groups show +I effect and –NO₂ group show –M effect
Order of acids strength
C > B > D > E > A

Concept:

Wurtz reaction -

• In this reaction, sodium metal reacts with two alkyl halides in presence of dry ether.
• A higher alkane obtained by the combination of two alkyl groups is achieved as a product along with the compound of sodium and halogen.
• This is a very important reaction for the formation of alkane.
• Reaction : RX + 2Na + RX → R-R + 2NaX.
• Wurtz reaction gives a product with an even number of carbons in it if only a single haloalkane is present in the reaction medium.

Explanation:
The given reaction will complete in two steps -

1. Free radical substitution reaction
2. Wurtz reaction

⇒ In the first step of the reaction free radical substitution of Br takes place into the given hydrocarbon.

• The given hydrocarbon can be methane as the final product is having carbon atoms less than four, which is only possible if we have an alkyl halide of only one carbon only.
• Methane on reaction with Br2 in presence of light gives methyl bromide.

​⇒ In the second reaction, the Wurtz reaction takes place to give a corresponding alkane.
The overall chemical reaction is -

∴ 'A' in the given reaction is methane.

Hence, the correct option is (3).

The correct answer is Symmetrical ether
Concept:-

• Ether: An ether is a compound that contains an oxygen atom bonded to two alkyl or aryl groups.
• Symmetrical Ether: A symmetrical ether is an ether in which the two alkyl or aryl groups attached to the oxygen atom are the same.
• Unsymmetrical Ether: An unsymmetrical ether is an ether in which the two alkyl or aryl groups attached to the oxygen atom are different.
• Mixed Ether: A mixed ether is an ether in which one of the alkyl or aryl groups attached to the oxygen atom is an alkyl group and the other is an aryl group.
• Heterocyclic Compound: A heterocyclic compound is a cyclic compound that contains at least one atom other than carbon in the ring.

Explanation:-

the strure of Diethyl ether

This is a symmetrical ether
Conclusion:-
Diethyl ether is Symmetrical ether

The answer is Benzal chloride.
Concept:-
Electrophilic Aromatic Substitution (EAS): Benzaldehyde undergoes EAS when treated with PCl5 to form benzal chloride.
Substitution Reaction: The reaction involves the substitution of an OH group in benzaldehyde with a chlorine atom.
Reaction with Phosphorus Halides: Phosphorus halides, such as PCl₅, are commonly used for chlorination reactions.
Explanation:-
Reaction of Benzaldehyde with PCl5: C₆H₅CHO+PCl₅−>C₆H₅Cl+POCl₃+HCl

Conclusion:-
So, The Benzaldehyde reacts with PCl5 to give Benzal chloride.

The correct option is the Grignard reagent.

Key Points

• When aldehyde is treated with Grignard reagent, it undergoes an addition reaction.
• It forms an addition compound, which on hydrolysis with dilute hydrochloric acid (HCl) produces primary and secondary alcohol.
• The Grignard reagent has the formula R-Mg-X, where R is an alkyl group, and X is a halide.
• It is also known as Organomagnesium halide.
• It is an organometallic reagent used for aldehydes and ketones.
• It is generally added to the carbonyl (CO) group of aldehydes and ketone compounds.

Additional Information Tollen's reagent

• Tollen's reagent is used for the identification or separation of aromatic and aliphatic aldehydes.
• It is an alkaline solution of ammonical AgNO₃ (silver nitrate).

Fehling's reagent

• Fehling's solution or reagent is the combination of sodium potassium tartrate, sodium hydroxide, and copper sulfate.
• It is used to differentiate the aldehydes and ketones.

Millon's reagent

• The millions reagent is a mixture of mercurous nitrate and mercuric nitrate in nitric acid with some nitrous acid.
• It is used to identify the occurrence of soluble proteins.

Finton's reagent

• It is a solution containing a mixture of hydrogen peroxide and ferrous ions.
• It is used as a catalyst in the advanced oxidation process to oxidize contaminants or wastewater particles.

Explanation:

Given:

CH₃-CH₂-OH CH₃-CH₂-Br

CH3-CH2-Br CH₂ = CH₂

CH2 = CH₂ CH3-CH2-OH

e we start a reaction with ethanol and the product Z we get is also ethanol.

When a drug binds to an enzyme from a site other than the active site, it is called an allosteric site. Binding to this site causes the change in shape of active site such that the substrate cannot recognise it.

Receptors are proteins that are embedded in the cell membrane with the binding site protruding outwards. They change the shape of the binding site to accommodate the incoming messenger and facilitate communication.

Agonists are drugs that replicate the behaviour and properties of the chemical messenger and activate the receptor. These are used when the actual messenger is not present in the body.

There are lots of different types of receptors in the body at different locations. They interact with different kinds of chemical messengers. Their selectivity for one messenger over the other is because of the difference in their binding sites, structure and composition of amino acids.

When there is a strong covalent bond between the enzyme and the drug, the enzyme is blocked permanently. This results in the degradation of the entire drug-enzyme complex and the synthesis of a new enzyme.

Non-competitive inhibitors are drugs that affect the catalytic activity of enzymes by changing the shape of the active site by binding to the enzyme at some other site. This prevents the substrate from binding to the enzyme.

The shape of the active site resembles a triangle, which means that the substrate should also have a similar shape. The drug that will inhibit the activity of this enzyme should closely resemble the substrate and block the active site. These are called competitive inhibitors.

Insulin consists of a chain of 51 amino acids and hence is a polypeptide. Estrogen and androgen are steroids, whereas epinephrine is an amine.

Amine hormones are water-soluble compounds which have amino groups and are structurally derived from amino acids. Oxytocin is a peptide hormone.

Epinephrine and norepinephrine are amine hormones that mediate response to external stimuli. Adrenaline plays an important role in fight or flight situations by increasing blood flow to muscles, blood sugar level and pulse rate.

Thyroxine is an iodinated derivative of tyrosine. Abnormally low levels of thyroxine leads to hypothyroidism, which causes enlargement of thyroid gland (goitre). Increases level of thyroxine causes hyperthyroidism.

Steroid hormones are produced by adrenal cortex and gonads. Hormones released by the adrenal cortex play a very important role in the functions of the bod.

If adrenal cortex does not function properly then one of the results may be Addison’s disease characterized by hypoglycaemia, weakness and increased susceptibility to stress. This may be fatal unless treated by glucocorticoids and mineralocorticoids.

Hormones are chemical substances produced by the endocrine glands in the human body. They are carried to different parts of the body through the blood stream. Because of the action of hormones as intercellular communicators, they are called chemical messengers.

Insulin is released in response to the rapid rise in blood glucose level. On the other hand, the hormone glucagon tends to increase the glucose level in blood. These two hormones together regulate the blood glucose level.

Oxytocin controls the contraction of the uterus during child birth and helps in the release of milk from mammary glands. Progesterone is responsible for the preparation of uterus for implantation of fertilised egg.

Low levels of iodine in the diet may lead to hypothyroidism and enlargement of the thyroid gland. This can be controlled by adding sodium iodide to table salt to form iodised salt.

Mineralocorticoids are steroid hormones which control the level of excretion of water and salt by the kidney, thus balancing the water and mineral levels as required.

Enzymes are biological catalysts produced by living cells. They differ from other catalysts in being highly selective and specific. Almost all enzymes are globular proteins. They are very specific for a particular reaction and a particular substrate.