Chemistry Test - 10

Acidity in ascending order =>  o-Nitrobenzoic acid >  p-Nitrobenzoic acid > m-Nitrobenzoic acid > Benzoic acid.

The acidity of ortho-nitrobenzoic acid is more as compared with para-nitrobenzoic acid because of the "ortho effect".

The explanation is relying on the steric inhibition of the resonance of the COOH group.

The ortho substituent forces the carboxyl group out of the plane of the benzene ring and decreases the resonance of the molecule.

At the same time carboxylate anion COO- have less sterically hindered and more apt to be in the energetically favorable planer configuration.

This makes an additional reason for the ortho-substituted acid to pass to the anion form thereby increasing its acidity as compared with the meta and para-substituted acids.

Two sucrose solutions of the same molality prepared in different solvents will have different freezing point depression.

This is because the molal depression in freezing point constant \(K_{b}\) is different for different solvents.

The freezing point depression \(=\Delta T_{f}=K_{b} \times m\)

Here, \(m\) is the molality of sucrose solution.

In the structure of \(C r O_{5}\), it has four \(O\) atoms as peroxide which have oxidation number \(=-1\) and one \(O\) as oxide (double bonded \(O)\) atom with oxidation number \(=-2\).

Let the oxidation number of \(C r\) is \(x\).

Then, \(x+4 \times(-1)+1 \times(-2)=0\) or, \(x=+6\)

The oxidation number of \(C r\) in \(C r O_{5}\) is \(+6\).

\(p-p\) overlap between \(\mathrm{B}\) and \(\mathrm{F}\) is maximum due to identical size and energy of \(p\) orbitals, so electron deficiency in boron of \(\mathrm{BF}_{3}\) is neutralized partially to the maximum extent by back donation.

In propanone((CH₃)₂CO), the functional group present is a ketone (- C=O) group.

Acetone also is known as Propanone is an organic compound with the formula (CH₃)₂CO.

In propanol (C₃H₇OH), the functional group present is an alcohol (- OH) group.

In propanoic acid (C₂H₅COOH), the functional group present is a carboxylic acid (- COOH) group.

In ethanal (CH₃CHO), the functional group present is an aldehyde(- CHO) group.

In propanal (C₂H₅CHO), the functional group present is an aldehyde(- CHO) group.

Zero-order reaction is a chemical reaction wherein the rate does not vary with the increase or decrease in the concentration of the reactants. Therefore, the rate of these reactions is always equal to the rate constant of the specific reactions (since the rate of these reactions is proportional to the zeroth power of reactants concentration).

The Differential form of a zero order reaction can be written as:

Rate \(=\frac{d A}{d t}=k[A]^{0}=k\)

Where 'Rate' refers to the rate of the reaction and '\(\mathrm k\)' is the rate constant of the reaction.

Grignard reagents form via the reaction of an alkyl or aryl halide with magnesium metal. The reaction is conducted by adding the organic halide to a suspension of magnesium in an ethereal solvent, which provides ligands required to stabilize the organomagnesium compound. The halide could also be all ( chlorine, bromine, iodine) except fluorine. It’s slightly easier to make Grignard from the iodides and bromides. The halide is that the “X” observed after we talk over Grignard reagents as \(" R M g X\) ".

The ether in the presence of which the reaction takes place is also called diethyl ether. It is synthesised by dehydration of ethanol using sulphuric acid.

The chemical action for the assembly of Grignard reagent is as follows:

\(R-X+M g \stackrel{\text { dryether }}{\longrightarrow} R-M g-X\) (Grignard reagent)

Primary battery is a batterywhich cannot be recharged.

• A primary cell is a battery (a galvanic cell) that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (rechargeable battery).
• Primary cells cannot be recharged effectively because their reaction products are not in contact with the electrodes.
• Primary cells are made in a range of standard sizes to power small household appliances such as flashlights and portable radios.

A functional isomer of Dimethyl ether is Ethanol.

It has the same chemical formula but different functional groups attached to them. e.g C₃H₆O

It has two functional isomers i.e.,

In the complex \(K _{2} Fe \left[ Fe ( CN )_{6}\right]\), both Fe atoms are in the same oxidation state.

Oxidation state of Fe in \(K _{2} Fe \left[ Fe ( CN )_{6}\right]\),

\(0=2+2 x -6\)

\(x =2\)

In the complex \(K _{2} Fe \left[ Fe ( CN )_{6}\right]\), both the iron atoms have \(+2\) oxidation state.Since six cyanide ions surround the iron atom, its coordination number is \(6 \).

The \(Fe ^{2+}\) ion in \(\left[ Fe ( CN )_{6}\right]^{4-}\) has outer electronic configuration of \(3 d ^{6}\). The complex is a low spin complex. It contains 0 unpaired electrons with a magnetic moment of 0 BM and is colourless.