Chemistry Test - 21

We know,

\(E _{ cell }=\frac{0.059}{2} \log \frac{1}{ C }\)

where, \(C =100\) times

\(E _{\text {cell }}=-\frac{0.059}{2} \log \frac{1}{100}\) \((\because\log \frac{1}{100}=-2)\)

\(=-\frac{0.059}{2} \times -2\)

\(=0.059 V \)

\(=59~ mV\)

Thus, if the \(Zn ^{2+} / Zn\) electrode is diluted to \(100\) times than the emf is decreaseof \(59~ mV\).

Molar conductivity increases with a decrease in concentrationstatement is true regarding Molar conductivity.

It is the conductance of volume V of a solution containing 1 mole of the electrolyte kept between two electrodes with the area of cross-section A and distance of unit length.

Molar conductivity has the \(\mathrm{Sl}\) unit \(\mathrm{S} \mathrm{} \mathrm{m}^{2} \mathrm{~mol}^{-1}\).

Molar conductivity increases with a decrease in concentration.

This is because the total volume V of the solution containing one mole of the electrolyte increases on dilution.

\(\Rightarrow \wedge \mathrm{m}=\mathrm{k} \times \mathrm{V}\)

Where,

\(\Lambda_{\mathbf{m}}\) - Molar conductivity

V - Volume, k - Specific conductance

\(\begin{aligned} & \mathrm{m}=\frac{1000 \times \mathrm{M}}{1000 \times \mathrm{d}-\mathrm{M} \times \mathrm{M} . \mathrm{W} \text { of solute }} \\ & =\frac{1000 \times 3}{1000 \times 1-(3 \times 58.5)}=3.64 \\ & =364 \times 10^{-2}\end{aligned}\)

\(\begin{aligned}& \lambda_{\mathrm{d}}=\frac{\mathrm{h}}{\mathrm{mv}}=\frac{\mathrm{h}}{\sqrt{2 \mathrm{mKE}}}=\frac{6.6 \times 10^{-34}}{\sqrt{2 \times 9 \times 10^{-31} \times 4.5 \times 10^{-29}}} \\& =\frac{6.6 \times 10^{-34}}{\sqrt{9^2 \times 10^{-60}}} \\& =\frac{6.6 \times 10^{-34}}{9 \times 10^{-30}}=\frac{6.6}{9} \times 10^{-4} \\& =7.3 \times 10^{-5} \mathrm{~m}\end{aligned}\)

Therefore Ans \(=7\)

Carbon belongs to the second period and Group 14. Silicon belongs to the third period and Group 14. If atomic number of carbon is 6, the atomic number of silicon is 14.

Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it.

The structure of the IF₇ molecule is Pentagonal Bipyramidal.

Iodine (I) is the central metal atom and Fluorine (F) is the monovalent atom. Also, it is a neutral molecule (i.e., the negative and positive charge is zero). In IF₇, the central atom I is attached to 7 fluorine atoms through 7 sigma bonds. So, the steric number is 7 here. Therefore, the hybridization of a central atom in IF₇ is sp³d³.

IF₇ has seven bond pairs and zero lone pairs of electrons.

In nitroprusside ion, the iron and NO exist as Fe(II) and \(NO^{+}\) rather than Fe(III) and NO. These forms can be distinguished by measuring the solid-state magnetic moment.

Nitroprusside ion is \(\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}\right]^{2-}\). If the central atom iron is present here in \(\mathrm{Fe}^{2+}\) form, its effective atomic number will be \(26-2+(6 \times 2)=36\) and the distribution of electrons in valence orbitals (hybridised and unhybridized) of the \(\mathrm{Fe}^{2+}\) will be

It has no unpaired electron. So this anionic complex is diamagnetic. If the nitroprusside ion has \(\mathrm{Fe}^{3+}\) and \(\mathrm{NO}\), the electronic distribution will be such that it will have one unpaired electron i.e. the complex will be paramagnetic.

Thus, magnetic moment measurement establishes that in nitroprusside ion, the Fe and NO exist as F(II) and \(NO^{+}\) rather than Fe(III) and NO.

Under ultra-violet light, three chlorine molecules add to benzene to produce benzene hexachloride, C₆H₆C_l6 which is also calledgammaxane.Benzene hexachloride is an isomer of hexachlorocyclohexane with a chemical formula C₆H₆C_l6.It is also known as Lindane or hexachloride.

Uses of Benzene hexachloride (C₆H₆C_l6):

• Benzene hexachloride is used as an insecticide on crops, in forestry, for seed treatment.
• It is used in the treatment of head and body lice.
• It is used in pharmaceuticals.
• It is used to treat scabies.
• It is used in shampoo.

Here, \(\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) with dissociation constant \(1.9 \times 10^{17}\) is more stable than \(\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) with dissociation constant \(2.6 \times 10^{37}\).

Higher is the dissociation constant lesser will be the stability of complex. So\(\mathrm{B}\) is more stable than \(\mathrm{A}\).

The Aufbau Principle states thatelectrons enter the lowest available energy level.

Then the electron goes to occupy thehigher atomic energy levels.This ruled is followed to write the electronic configuration of atoms in theirground state.

When in theexcited state, the electronsmight vacant the lower energystate and move on to a higher energy state.

The order follows that the lower ( n + l ) value of atomic orbital will have lower energy, where n = principal quantum number and l = azimuthal quantum number.

When ( n + l ) is the same, for two orbitals, the orbital having a lower value of n will be filled first.

3d and 4p both have ( n + l ) values of 5 but 3d is filled first because it has n = 3.

The final series is:

\(1 s<2 s<2 p<3 s<3 p<4 s<3 d<4 p<5 s<4 d<5 p<6 s<4 f<5 d<6 p<7 s<5 f<6 d<7 p<8 s\)

So, The Aufbau Principle states that electrons enter the lowest available energy level.