Class 12th

This is a long answer type question as classified in NCERT Exemplar

(a) Cumene is the beginning element for the industrial production of phenol.

(b)

When bromine water is used to treat phenol. As a whitish precipitate, 2,4,6-tribromophenol is formed

(c) Benzene is normally halogenated in the presence of a Lewis acid, such as FeBr3, which polarises the halogen molecule. Even in the absence of Lewis acid, the polarisation of the bromine molecule occurs in the case of phenol. It's because the benzene ring's —OH group has a strong activating impact.

This is a long answer type question as classified in NCERT Exemplar

In case of anisole, methylphenyl oxonium ion, is formed by protonation of ether. The bond between O—CH₃ is weaker than the bond between O—C₆H₅ because the carbon of phenyl group is sp2 hybridised and there is partial double bond character. Therefore, the attack by I- ion breaks O—CH₃ bond to form CH₃I. Phenols do not react further to give halides because the sp2 hybridised carbon of phenol cannot undergo nucleophilic substitution reaction needed for conversion to the halide.

After the NEET results, Indian students can make NSMU Russia application on the official wesbite of this university. 

Indian students are required to clear 12^th standard with a minimum of 50% in 12^th class with Physics, Chemistry, Maths. A certain level of English and Russian is also required, however the students don't have to take IELTS, or TOEFL.

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Correct option:  C

A catalyst allows a chemical reaction to occur at a faster rate or under different conditions than it would otherwise. As a result, a catalyst affects the reaction's enthalpy change, or heat. As a result, in the presence of the reaction, the enthalpy does not vary, i.e., it remains constant, and no heat is produced or absorbed.

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Correct option: B

The Arrhenius equation can be used to calculate the activation energy of a chemical process. At two temperatures, this determines the rate constants.

2.303log = $\frac{{\mathrm{K}}_2}{{\mathrm{K}}_1}$ = $\frac{{\mathrm{E}}_{\mathrm{a}}}{\mathrm{R}}$       $\frac{{\mathrm{T}}_2-{\mathrm{T}}_1}{{\mathrm{T}}_1{\mathrm{T}}_2}$

This is a Assertion and Reason Type  as classified in NCERT Exemplar

Ans: Correct Option: (iv)

  (i) Copper sulfate can't be stored in zinc vessels due to less reactive nature than zinc due to the negative standard reduction value of zinc.

So both assertion and reason are false. Therefore, this option is incorrect.

This is a Assertion and Reason Type as classified in NCERT Exemplar

Correct option: C

The assertion is valid, but the reasoning is erroneous because Arrhenius equation rate constants are accurate for both simple and complex molecules with suitable orientation during effective collision and sufficient kinetic energy to cause chemical change.

This is a Assertion and Reason Type  as classified in NCERT Exemplar

Ans: Correct Option: (i)

(i)At the equilibrium stage E $°$ _cell = 0 and current stops flowing in the cell. Therefore, the assertion is correct, the reason is correct and the reason is the correct explanation for assertion. Therefore, this option is correct

(ii)  Assertion is correct, the reason is correct and the reason is the correct explanation for assertion. Therefore, this option is incorrect