Surface Chemistry & Solid State · JEE Main previous year questions

10 mL of 1mM surfactant solution forms a monolayer covering $0.24\mathrm{c}{\mathrm{m}}^2$ on a polar substrate. If the polar head is approximated as cube, what is its edge length?

1. A.$1.0\mathrm{pm}$
2. B.$2.0\mathrm{nm}$
3. C.$0.1\mathrm{nm}$
4. D.$2.0\mathrm{pm}$

Consider the bcc unit cells of the solids 1 and 2 with the position of atoms as shown below. The radius of atom B is twice that of atom A. The unit cell edge length is 50% more in solid 2 than in 1. What is the approximate packing efficiency in solid 2? [Figure: Solid 1 – bcc cell with atom A at all corners and at the body centre. Solid 2 – bcc cell with atom A at all corners and atom B at the body centre.]

1. A.45%
2. B.90%
3. C.75%
4. D.65%

The coordination number of Th in ${\mathrm{K}}_4[\mathrm{Th}({\mathrm{C}}_2{\mathrm{O}}_4{)}_4(\mathrm{O}{\mathrm{H}}_2{)}_2]$ is : $({\mathrm{C}}_2{\mathrm{O}}_4^{2-}=\text{Oxalato})$

1. A.14
2. B.10
3. C.8
4. D.6

The radius of the largest sphere which fits properly at the centre of the edge of a body centred cubic unit cell is : (Edge length is represented by 'a')

1. A.0.134 a
2. B.0.067 a
3. C.0.047 a
4. D.0.027 a

Among the colloids cheese (C), milk (M), and smoke (S), the correct combination of the dispersed phase and dispersion medium, respectively is :

1. A.C : liquid in solid ; M : liquid in liquid ; S : solid in gas
2. B.C : liquid in solid ; M : liquid in solid ; S : solid in gas
3. C.C : solid in liquid ; M : liquid in liquid ; S : gas in solid
4. D.C : solid in liqid ; M : solid in liquid ; S : solid in gas

The alkaline earth metal nitrate that does not crystallise with water molecules, is :

1. A.$\mathrm{Mg}(\mathrm{N}{\mathrm{O}}_3{)}_2$
2. B.$\mathrm{Sr}(\mathrm{N}{\mathrm{O}}_3{)}_2$
3. C.$\mathrm{Ca}(\mathrm{N}{\mathrm{O}}_3{)}_2$
4. D.$\mathrm{Ba}(\mathrm{N}{\mathrm{O}}_3{)}_2$

1. A.${\mathrm{P}}^2$
2. B.${\mathrm{P}}^{\frac{1}{4}}$
3. C.${\mathrm{P}}^{\frac{1}{2}}$
4. D.$\mathrm{P}$

Which one of the following is not a property of physical adsorption?

1. A.Higher the pressure, mre the adsorption
2. B.Lower the temperature, more the adsorption
3. C.Greater the surface area, more the adsorption
4. D.Unilayer adsorption ocurs

Which of the following statements about colloids is False ?

1. A.Freezing point of colloidal solution is lower than true solution at same concentration of a solute.
2. B.Colloidal particles can pass through ordinary filter paper.
3. C.When silver nitrate solution is added to potassium iodide solution, a negatively charged colloidal solution is formed.
4. D.When excess of electolyte is added to colloidal solution, colloidal particle will be precipitated.

Adsorption of a gas on a surface follows Freundlich adsorption isotherm. Plot of $\log \frac{x}{m}$ versus $\log \mathrm{p}$ gives a straight line with slope equal to 0.5, then: ( $\frac{x}{m}$ is the mass of the gas adsorbed per gram of adsorbent)

1. A.Adsorption is independent of pressure.
2. B.Adsorption is proportional to the pressure.
3. C.Adsorption is proportional to the square root of pressure.
4. D.Adsorption is proportional to the square of pressure.

For a linear plot of log (x/m) versus log p in a Freundlich adsorption isotherm, which of the following statements is correct ? (k and n are constants)

1. A.Both k and 1/n appear in the slope term.
2. B.1/n appears as the intercept.
3. C.Only 1/n appears as the slope
4. D.log (1/n) appears as the intercept.

Sodium metal crystallizes in a body centred cubic lattice with a unit cell edge of 4.29 Å . The radius of sodium atom is approximately :

1. A.5.72 Å
2. B.0.93 Å
3. C.1.86 Å
4. D.3.22 Å

$\mathrm{CsCl}$ crystallises in body centred cubic lattice. If 'a' is its edge length then which of the following expressions is correct?

1. A.$r_{C{s}^{+}}+r_{C{l}^{-}}=\frac{\sqrt{3}}{2}a$
2. B.$r_{C{s}^{+}}+r_{C{l}^{-}}=\frac{3}{2}a$
3. C.$r_{C{s}^{+}}+r_{C{l}^{-}}=\sqrt{3}a$
4. D.$r_{C{s}^{+}}+r_{C{l}^{-}}=3a$

Colloidal solutions can be purified by

1. A.emulsification
2. B.electrodialysis
3. C.peptization
4. D.using Tyndall effect

The radius of a calcium ion is $94\mathrm{pm}$ and of the oxide ion is $146\mathrm{pm}$. The possible crystal structure of calcium oxide will be

1. A.tetrahedral
2. B.trigonal
3. C.octahedral
4. D.pyramidal

A solid has a 'bcc' structure. If the distance of nearest approach between two atoms is $1.73\mathring{\mathrm{A}}$, the edge length of the cell is

1. A.$314.20\mathrm{pm}$
2. B.$1.41\mathrm{pm}$
3. C.$200\mathrm{pm}$
4. D.$216\mathrm{pm}$

If $x$ is the mass of the gas adsorbed on mass $m$ of the adsorbent at pressure $p$, Freundlich adsorption isotherm gives a straight line on plotting

1. A.$x/m\mathrm{vs}p$
2. B.$x/m\mathrm{vs}1/p$
3. C.$\log x/m\mathrm{vs}\log p$
4. D.$\log x/m\mathrm{vs}p$

Copper crystallizes in fcc with a unit cell length of 361 pm. What is the radius of copper atom?

1. A.108 pm
2. B.127 pm
3. C.157 pm
4. D.181 pm

Total volume of atoms present in a face-centred cubic unit cell of a metal is (r is atomic radius) :

1. A.$20/3\pi r^3$
2. B.$24/3\pi r^3$
3. C.$16/3\pi r^3$
4. D.$12/3\pi r^3$

In Langmuir’s model of adsorption of a gas on a solid surface

1. A.the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered
2. B.the adsorption at a single site on the surface may involve multiple molecules at the same time
3. C.the mass of gas striking a given area of surface is proportional to the pressure of the gas
4. D.the mass of gas striking a given area of surface is independent of the pressure of the gas

The volume of a colloidal particle, $V_{\mathrm{C}}$ as compared to the volume of a solute particle in a true solution $V_{\mathrm{S}}$, could be

1. A.$\frac{V_{\mathrm{C}}}{V_{\mathrm{S}}}\simeq 1$
2. B.$\frac{V_{\mathrm{C}}}{V_{\mathrm{S}}}\simeq 10^{-3}$
3. C.$\frac{V_{\mathrm{C}}}{V_{\mathrm{S}}}\simeq 10^3$
4. D.$\frac{V_{\mathrm{C}}}{V_{\mathrm{S}}}\simeq 10^{23}$

The disperse phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged, respectively, which of the following statements is NOT correct?

1. A.magnesium chloride solution coagulates, the gold sol more readily than the iron (III) hydroxide sol.
2. B.sodium sulphate solution causes coagulation in both sols
3. C.mixing the sols has no effect
4. D.coagulation in both sols can be brought about by electrophoresis

What type of crystal defect is indicated in the diagram below? $$\begin{array}{llllll}\mathrm{N}{\mathrm{a}}^{+}& \mathrm{C}{\mathrm{l}}^{-}& \mathrm{N}{\mathrm{a}}^{+}& \mathrm{C}{\mathrm{l}}^{-}& \mathrm{N}{\mathrm{a}}^{+}& \mathrm{C}{\mathrm{l}}^{-}\\ \mathrm{C}{\mathrm{l}}^{-}& \square & \mathrm{C}{\mathrm{l}}^{-}& \mathrm{N}{\mathrm{a}}^{+}& \square & \mathrm{N}{\mathrm{a}}^{+}\\ \mathrm{N}{\mathrm{a}}^{+}& \mathrm{C}{\mathrm{l}}^{-}& \square & \mathrm{C}{\mathrm{l}}^{-}& \mathrm{N}{\mathrm{a}}^{+}& \mathrm{C}{\mathrm{l}}^{-}\\ \mathrm{C}{\mathrm{l}}^{-}& \mathrm{N}{\mathrm{a}}^{+}& \mathrm{C}{\mathrm{l}}^{-}& \mathrm{N}{\mathrm{a}}^{+}& \square & \mathrm{N}{\mathrm{a}}^{+}\end{array}$$

1. A.Interstitial defect
2. B.Schottky defect
3. C.Frenkel defect
4. D.Frenkel and Schottky defects

The formation of gas at the surface of tungsten due to adsorption is the reaction of order :

1. A.0
2. B.1
3. C.2
4. D.insufficient data

Na and Mg crystallize in BCC and FCC type crystals respectively, then the number of atoms of Na and Mg present in the unit cell of their respective crystal is :

1. A.4 and 2
2. B.9 and 14
3. C.14 and 9
4. D.2 and 4