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Haloalkanes undergo nucelophilic substitution reactions owing to the polarity of CX bond. The nucleophile reacts with the haloalkane on the carbon possessing a partial positive charge holding the halogen atom. The halogen atom X is replaced by a nucleophile. Depending on the kinetics and mode of bond breaking, the mechanism can be either SN1 or SN2 reaction. The rate of SN1 reaction is governed by the stability of carbocation and in SN2 reaction, the rate of reaction is governed by steric factor. Chirality is the main factor in both SN1and SN2. In SN1 reaction, the chirality of alkyl halide is accompanied by racemization of the product, while in SN2 reaction, the product is characterized by inversion of configuration. The structure of alkyl halide and the nature of the solvent also governs the mechanism of the substitution.
What is meant by the term racemic mixture?

The Gattermann-Koch reaction is used in the industrial preparation of benzaldehyde.
The electrophile involved in this reaction is:

The order of a reaction where half life changes from 150 min to 75 min when the concentration of reactant is changed from 0.4 M to 1.6 M respectively is :

The decreasing order of basicity of the following amines in aqueous solution is
(A) Ethylamine
(B) N-Ethylethanamine
(C) N,N-Diethylethanamine
(D) Benzamine
Choose the correct answer from the options given below:

Which of the following statements about hormones is incorrect?

An element has a cubic close packing (ccp) structure with an edge length 297 pm . The density of mass \(=107.9 g / mol\).)
the element is (Given molar mass = \(107.9 g / mol\).)

Match List - I (Common name) with List - II (IUPAC name)

List - I (Common Name)	List - II (IUPAC name)
(A) Aniline	(I) N-Phenylethanamide
(B) Acetanilide	(II) Benzenamine
(C) Sulphanilic acid	(III) Prop-2-en-1-amine
(D) Allylamine	(IV) p-aminobenzene sulphonic acid

Choose the correct answer from the options given below:

Match List-l with List-ll

List-l (Aspect)	List-II (Explanation)
(A) Productivity	(I) Photosynthetically active radiation
(B) Nutrient Cycling	(II) Breakdown of organic matter
(C) Energy Flow	(III) Rate of biomass production
(D) Decomposition	(IV) Sedimentary

Choose the correct answer from the options given below:

Match List - I With List - II

List - I	List - II
(A) The area of parallelogram determined by vectors \(2 \hat{i}\) and \(3 \hat{j}\)	(I) 2
(B) The value of \((\hat{i} \times \hat{j}) \cdot \hat{k}+(\hat{j} \times \hat{k}) \cdot \hat{i}\)	(II) 4
(C) The value of a for which the vectors \(2 \hat{i}-3 \hat{j}+4 \hat{k}\) and \(a \hat{i}-6 \hat{j}+8 \hat{k}\) are collinear.	(III) 0
D. The value of \(\lambda\) for which the vectors \(2 \hat{i}+\hat{j}+\hat{k}\) and \(2 \hat{i}-4 \hat{j}+\lambda \hat{k}\) are perpendicular.	(IV) 6

Choose the correct answer from the options given below.

The solution of the differential equation \((\cot y) d x=x d y\) is:

There are two kinds of nucleases - exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA. The cutting of DNA by restriction endonucleases results in the fragments of DNA. These fragments can be separated by a technique known as gel electrophoresis. Since DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium/matrix. Small volume cultures cannot yield appreciable quantities of products. To produce in large quantities, the development of bioreactors, where large volumes (100 - 1000 litres) of culture can be processed, was required. Thus, bioreactors can be thought of as vessels in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial plant, animal or human cells. PCR stands for Polymerase Chain Reaction. In this reaction, multiple copies of the gene (or DNA) of interest are synthesised in vitro using two sets of primers (small chemically synthesised oligonucleotides that are complementary to the regions of DNA) and the enzyme DNA polymerase.
Identify the incorrect fact about the PCR?

Amniocentesis is used in the prenatal diagnosis of:

A letter is known to have come either from KOLKATA or TATANAGAR. On the envelope just two consecutive letters TA are visible. The probability that letter has come from TATANAGAR is