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.

Stereoisomers that are superimposable mirror images are identical, not enantiomers

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

• A is correct: Boiling points of alcohols increase with the number of carbon atoms due to increased van der Waals forces.
• B is incorrect: Boiling points decrease with branching due to reduced surface area and van der Waals forces.
• C is incorrect: Boiling points of alcohols are higher than haloalkanes of comparable molecular mass due to hydrogen bonding.
• D is correct: Boiling points of alcohols are higher than hydrocarbons of comparable molecular mass due to hydrogen bonding.
• E is correct: High boiling points of alcohols are due to intermolecular hydrogen bonding. Thus, A, D, and E are correct.
• Answer: A (A, D, and E only).

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 structure of Diethyl ether

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

When benzaldehyde (C₆H₅CHO) reacts with phosphorus pentachloride (PCl₅), the reaction replaces the carbonyl oxygen with two chlorine atoms.

Reaction:

C₆H₅CHO + PCl₅ → C₆H₅CHCl₂ + POCl₃

Product Formed:

• The main organic product is benzal chloride (C₆H₅CHCl₂).

• Phosphoryl chloride (POCl₃) is a by-product.

Explanation:

• PCl₅ acts as a chlorinating agent.

• It converts the aldehyde group (–CHO) into a geminal dichloride (–CHCl₂).

So, 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 Millons 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.

Transition metals typically have high melting points due to strong metallic bonding between metal atoms.

Transition metals form colored compounds due to the absorption of light caused by d-d transitions, where electrons move between d-orbitals.

Transition metals can exist in multiple oxidation states because the energy difference between their s and d orbitals is small enough to allow for easy electron transfer.

Transition metals act as catalysts by providing an alternate pathway with lower activation energy, making chemical reactions faster.

Transition metals are good conductors of both electricity and heat due to their free electrons in the d-orbitals.

Geometrical isomerism arises when ligands are arranged differently in space, leading to cis and trans isomers.

Stereoisomerism involves different spatial arrangements of ligands, even though their bonding remains the same.

Geometrical isomerism involves ligands arranged in different spatial configurations, such as cis and trans.

Optical isomerism occurs when a complex can exist in two mirror-image forms, like left and right hands.

Cis and trans isomerism is a common example of stereoisomerism in octahedral coordination complexes.

• Statement (A) is correct: Higher temperature increases collision frequency.
• (B) is correct: Catalysts lower activation energy to increase reaction rate.
• (C) is incorrect: Catalysts do not alter the equilibrium position, only the rate.
• (D) is correct: Increased reactant concentration increases collision frequency and thus the rate.

Answer: B (A, B, and D only).

• Statement (A) is correct: The rate law expresses the reaction rate in terms of reactant concentrations.
• Statement (B) is incorrect: The rate constant (k) depends on temperature and catalysts, not reactant concentrations.
• Statement (C) is correct: The rate law is determined experimentally, not from stoichiometry.
• Statement (D) is correct: For a first-order reaction, k has units of time^-1.

Answer: B (A, C, and D only).

When a compound binds to a site other than the active site (called an allosteric site), it changes the active site’s shape, preventing substrate recognition. Options A (inactive site), B (binding site), and C (non-competitive site) do not specifically describe this regulatory mechanism. Answer: D (allosteric site).

Receptors are proteins in the cell membrane with binding sites that change shape to fit messengers, facilitating communication. Option A (constant shape) is incorrect; B, C, and D are correct. Answer: A (They have constant shape).

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.

A strong covalent bond between an enzyme and drug causes permanent inhibition, leading to the drug-enzyme complex being metabolized or cleared, necessitating new enzyme synthesis. Options A, B, and C imply temporary effects. Answer: D (The body synthesizes a new enzyme).

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

"Epinephrine (also known as adrenaline) is the fight or flight hormone, increasing blood flow, sugar levels, and pulse rate. Dopamine, insulin and thyroxine are unrelated. Answer: A (Epinephrine).

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.

Oxytocin controls uterine contractions during childbirth and milk release postpartum. Progesterone prepares the uterus for implantation. Answer: D (Oxytocin).

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, highly selective and specific to particular substrates, mostly globular proteins. Answer: C (Highly selective).