The covalent bond is formed by the sharing of electrons between two atoms. As the element B (which belongs to group 14) has 4 valence electrons which it can share with two elements of C type (from group 16) electrons to complete the octet of each included atom.

For ${\mathrm{CH}}_3\mathrm{Br}$:

Atomic mass:

$=(12\times 1)+(1\times 3)+(80\times 1)$

$=95$

For ${\mathrm{CH}}_3\mathrm{Cl}$:

Atomic mass:

$=(12\times 1)+(1\times 3)+(35.5\times 1)$

$=50.5$

For ${\mathrm{H}}_2\mathrm{O}$:

Atomic mass:

$=(16\times 1)+(2\times 1)$

$=18$

According to above data regarding atomic masses of compounds, the decreasing order will be:

${\mathrm{CH}}_3\mathrm{Br}>{\mathrm{CH}}_3\mathrm{Cl}>$ ${\mathrm{H}}_2\mathrm{O}$

$35\mathrm{\%}\mathrm{HCl}$ by mass means in $100\mathrm{gm}\mathrm{HCl}$ solution $35\mathrm{gm}\mathrm{HCl}$ present.

Now, volume of $100\mathrm{gm}\mathrm{HCl}$ solution

$=\frac{100}{1.46}\mathrm{ml}$

$=\frac{\frac{100}{1.46}}{1000}\mathrm{I}$

$\text{ Moles of }\mathrm{HCl}=\frac{35}{36.5}\text{ moles of solute }$

$\text{ Now, molarity }=\frac{\frac{35}{36.5}}{\text{ volume of solution ( in }\mathrm{L})}$

$=\frac{\frac{35}{36.5}}{\frac{100}{1.46}}=14$

Solids have a regular repeated molecular pattern in three dimensional space and this is due to their property of high inter-molecular forces. But in liquids and gases, the arrangement of molecular pattern is irregular.

Internal energyis a quantity that represents the total energy of the system.

In 1897, great physician J.J. Thompson, conducted his first cathode ray tube experiment.

Thompson, conducted this experiment to prove that rays emitted from an electron gun are inseparable from the latent charge. He built his cathode ray tube with a metal cylinder on the other end. The metal had two small diversions(slits), leading to electrometer that could measure small electric charge.

${\mathrm{Ni}}^{2+}$cannot be a ligand.

The ions/molecules bound to the central atom/ion is called a ligand. ${\mathrm{Ni}}^{2+}$ is a metal ion, and according to Werner, the secondary valences can be satisfied only by neutral molecules or negative ions. ${\mathrm{Cl}}^{-},{\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{NH}}_3$ are all possible ligands.

Glycerol is Trihydric alcohol.

Compounds having one −OH group is called monohydric alcohol.

Compounds having two −OH group is called dihydric alcohol.

Compounds having three −OH group is called trihydric alcohol.

Image of glycerol is given below, it has three −OH group

In oxidation, an element looses its electrons.

There is $+3$ oxidation state means no. of loss of electrons is 3, and that 2 electrons are released from $4{\mathrm{s}}^2$ orbital and 1 electron from $3\mathrm{d}$ orbital to attain half filled stability.

Therefore, $\left[\mathrm{Ar}\right]$ has 18 electrons and 5 electrons in $3\mathrm{d}$ orbital as per given.

Therefore, actual configuration will be $[Ar{]}^{18}3d^{6}4s^2$. Therefore, atomic number will be $18+6+2=26$.

This is Fe having atomic number 26.