Solids - Class 12 Chemistry - Chapter 11 - Notes, NCERT Solutions & Extra Questions
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Extra Questions - Solids | NCERT | Chemistry | Class 12
An element occurring in the bcc structure has unit cells.
The total number of atoms of the element in these cells will be
(A) $24.16 \times 10^{23}$ (B) $36.18 \times 10^{23}$ (C) $6.04 \times 10^{23}$ (D) $12.08 \times 10^{23}$
In a body-centered cubic (bcc) structure, each unit cell contains two atoms. Therefore, the number of atoms in $12.08 \times 10^{23}$ unit cells is calculated by multiplying the number of unit cells by the number of atoms per unit cell:
$$ \text{Total atoms} = 2 \times 12.08 \times 10^{23} = 24.16 \times 10^{23} \text{ atoms}. $$
Thus, the correct answer is (A) $24.16 \times 10^{23}$.
Lattice energy of an ionic compound depends upon
A Charge on the ion only
B Size of the ion only
C Packing of ions only
D Charge on the ion and size of the ion
The correct option is D: Charge on the ion and size of the ion.
The lattice energy ($U$) of an ionic compound is influenced by both the charge on the ions and the size of the ions. This dependency can be mathematically represented as:
$$ U \propto \frac{\text{charge on ions}}{r^{+} + r^{-}} $$
where $r^{+}$ and $r^{-}$ denote the radii of the cation and anion, respectively. This formula shows that lattice energy is directly proportional to the charges of the ions involved and inversely proportional to the sum of the ionic radii.
Which of the following represents properties of glass?
A) Gas
B) Amorphous solid
C) Brittle
D) Made of $\mathrm{CaCO}_{2}$
The correct properties of glass among the provided options are:
B) Amorphous solid
C) Brittle
Glass is characterized by its unique amorphous structure and brittle nature. It is typically composed of silica and various silicates, not $\mathrm{CaCO}_{2}$ (calcium carbonate), which is another material entirely. Hence, options A and D are incorrect. Amorphous solids like glass lack the long-range order seen in crystalline solids, contributing to properties such as brittleness.
The low melting point and the high solubility of $\mathrm{LiCl}$ in organic solvents is due to:
A Covalent nature because of polarising power of small $\mathrm{Li}^{+}$ on $\mathrm{Cl}^{-}$
B Very low lattice energy
C Low hydration energy of $\mathrm{Li}^{+}$ in water
D Low hydration energy of $\mathrm{Cl}^{-}$ in water
The correct answer is Option A: Covalent nature due to the polarising power of small $\mathrm{Li}^+$ on $\mathrm{Cl}^-$.
Although $\mathrm{LiCl}$ possesses a high lattice energy, the significant factor influencing its properties is the covalent character induced by the polarization of $\mathrm{Cl}^-$ by the small $\mathrm{Li}^+$ ion. This polarization leads to a scenario where $\mathrm{LiCl}$ exhibits characteristics typical of covalent compounds, such as a low melting point and high solubility in organic solvents. This behavior is primarily due to the covalent nature resulting from the strong polarizing power of the $\mathrm{Li}^+$ ion.
Which one of the following crystals does not exhibit Frenkel defect?
A $\mathrm{AgBr}$
B $\mathrm{AgCl}$
C $\mathrm{KBr}$
D $\mathrm{ZnS}$
The correct answer is C $\mathrm{KBr}$.
$\mathrm{KBr}$ is known to exhibit a Schottky defect rather than a Frenkel defect. This is characteristic of ionic compounds with similarly sized cations and anions.
On the other hand, $\mathrm{AgBr}$, which is listed as option A, shows both Schottky and Frenkel defects. The Frenkel defect is typically found in ionic solids with a considerable size difference between cations and anions and these often have lower coordination numbers and stronger ionic character.
Which of the following solids are not polyhedrons?
A. Sphere
B. Cylinder
C. Cuboid
D. Cone
The solids that are not polyhedrons are:
- A. Sphere
- B. Cylinder
- D. Cone
A polyhedron is defined as a three-dimensional figure made up of flat polygonal faces. The sphere, cylinder, and cone do not meet this criterion as they are comprised of curved surfaces rather than polygonal regions.
On the other hand, a cuboid is indeed a polyhedron because it is composed entirely of polygonal faces (specifically rectangles).
In solids, the strength of intermolecular forces of attraction is:
A) less than liquid
B) less than gases
C) equivalent to liquid
D) higher than liquid and gases
The correct answer is D) higher than liquid and gases.
Intermolecular forces are responsible for holding particles together within a material. These forces differ across the various states of matter.
Considering all three states of matter, the strength of the intermolecular forces is in the following order: $$ \text{gases} < \text{liquids} < \text{solids} $$
Thus, in solids, the intermolecular forces are the strongest compared to liquids and gases.
If $N$ is the number of spheres in the unit cell, then the total number of tetrahedral voids is:
A) $2 \mathrm{~N}$
B) $3 \mathrm{~N}$
C) $4 \mathrm{~N}$
The correct answer is A) $2N$.
In crystallography, the number of tetrahedral voids in a unit cell is twice the number of spheres (atoms or particles) it contains. Thus, if $N$ represents the number of spheres in the unit cell, the total number of tetrahedral voids is:
$$ 2N $$
Name 2 elements each which exist in
- Solid state, 2) liquid state, 3) gas state
Sure, here are examples of elements in different states of matter at room temperature:
-
Solid State Elements:
- Copper ($\text{Cu}$)
- Iron ($\text{Fe}$)
-
Liquid State Elements:
- Mercury ($\text{Hg}$)
- Bromine ($\text{Br}_2$)
-
Gas State Elements:
- Helium ($\text{He}$)
- Argon ($\text{Ar}$)
These examples include typical representatives of elements in each state under standard conditions (room temperature and atmospheric pressure).
Pure orthoboric acid exists as a:
A) solid B) liquid C) gas
The correct answer is A) solid.
Orthoboric acid, also known simply as boric acid, naturally exists in the form of solid. It typically crystallizes into soft, needle-like structures.
Answer:
A solid is crystalline, has a high melting point, and is water-soluble. Describe the nature of the solid.
Solution
The solid described is likely an ionic solid based on its distinct properties:
- Crystalline structure - indicates that the particles are organized in a regular, repeating pattern.
- High melting point - implies that a significant amount of energy is necessary to disrupt the solid's lattice, indicating strong bonds.
- Water-soluble - suggests that the solid is polar, as water, a polar solvent, dissolves polar compounds effectively.
These characteristics are typical of ionic solids, where oppositely charged ions are held together by strong ionic bonds in a lattice structure.
At a particular temperature, the solution which cannot dissolve more solute is called $\qquad$
A. Saturated solution
B. Unsaturated solution
C. Supersaturated solution
D. Solid solution
The correct answer is A. Saturated solution.
A saturated solution is defined as a solution that can't dissolve any more solute at a given temperature. Once the maximum amount of solute has been dissolved, adding more will result in excess solute accumulating as a precipitate or sediment since it cannot be absorbed into the solvent.
How will you determine the density of irregular solids that are insoluble in water?
To determine the density of irregular solids that are insoluble in water, follow these steps:
-
Measure the Mass (M): Use a scale to weigh the object to find its mass. This step is straightforward as it involves simply placing the object on a weighing scale.
-
Determine the Volume (V): To find the volume of an irregular object, utilize the displacement method:
- Fill a graduated container with water to a certain level and mark this initial water level.
- Submerge the irregular solid completely in the water. Ensure the object is insoluble and does not dissolve.
- The water level will rise due to the displacement caused by the object. Mark the new water level.
- Remove the object from the water. Now, measure the volume of water needed to reach from the initial to the new water level using a graduated cylinder or a measuring jug. This measured volume equals the volume of the object.
-
Calculate Density: Once you have both mass and volume, calculate the density using the formula: $$ \text{Density} = \frac{\text{Mass}}{\text{Volume}} $$ where:
- Density is measured in units like grams per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³).
- Mass is in units such as grams (g) or kilograms (kg).
- Volume is in cubic centimeters (cm³) or cubic meters (m³).
This method accurately determines the density of irregular, insoluble solids using simple tools and principles.
Arrange solid, liquid, gas on the basis of intermolecular space between the particles in ascending order.
A Solid < Liquid < Gas
B Gas < Solid < Liquid
C Liquid < Gas < Solid
D Liquid < Solid < Gas
The correct option is A Solid < Liquid < Gas.
In different states of matter, intermolecular spaces vary significantly, leading to different physical properties. Specifically:
-
Gases have the largest intermolecular spaces; particles are far apart and move freely because the intermolecular forces are the weakest. This allows gases to expand and fill their containers.
-
Liquids have smaller intermolecular spaces compared to gases. The particles are closer together but still have enough space to move around each other, which is why liquids have a fixed volume but can change shape.
-
Solids have the smallest intermolecular spaces, with particles tightly packed in a fixed arrangement. This tight packing results from strong intermolecular forces, allowing solids to maintain both a fixed volume and shape.
Hence, in terms of increasing intermolecular space, the arrangement is Solid < Liquid < Gas.
The active mass of a solid is taken to be unity - true or false?
A) True
B) False
The correct option is A) True.
Active mass is considered the effective concentration of a substance in a reaction. It reflects the reactivity of the substance and is directly connected to the rate at which the substance undergoes a chemical reaction. For liquids and gases, the active mass is typically represented by their molar concentrations. However, for solids, it is a convention to consider their active mass as unity, regardless of their actual quantity.
This assumption is based on the idea that the reaction occurs on the surface of the solid and hence, the total mass of the solid remains effectively constant during the reaction. This is especially relevant in reversible reactions where conditions such as constant temperature are maintained and the physical state of solids does not change appreciably to influence the reaction dynamics. Thus, variations in the concentration of the solid do not materially impact the reaction mechanism as explained in the context of chemical equilibrium.
Initially, the "Law of Mass Action" incorporated terms like "activity" and "active mass," but over time this law has evolved to what we currently use as the Law of Chemical Equilibrium. This modern day law does not generally use the concept of active mass for solids, recognizing them simplistically as having a constant active mass of unity. This convention acknowledges historical contributions while simplifying modern chemical analysis and predictions involving solids in reactions.
The correct order of compressibility is:
A. Solid > Liquid > Gas
B. Solid > Gas > Liquid
C. Gas > Liquid > Solid
D. Gas > Solid > Liquid
The provided question involves determining the correct order of compressibility among solids, liquids, and gases. Compressibility refers to the ability of a substance to decrease in volume under pressure.
From the explanation:
Gases are highly compressible. This is because the particles in a gas are far apart, providing much space to be compressed. Gases can easily be compressed into cylinders, like oxygen and nitrogen, which implies they have the highest compressibility.
Liquids come next in terms of compressibility. They are less compressible than gases because the particles are closer together, but they still have small spaces between them that allow for some compression.
Solids are the least compressible. The particles in a solid are tightly packed with little space between them, making them practically incompressible under normal conditions.
Given this information, the order of compressibility from most to least is: $$ \text{Gas} > \text{Liquid} > \text{Solid} $$ Therefore, the correct answer to the question "What is the correct order of compressibility?" is Gases being more compressible than Liquids, which in turn are more compressible than Solids.
Which of the following is the correct decreasing order of the elements: Iodine (volatile solid), Bromine (brown liquid), and Chlorine (greenish yellow gas) in terms of force of attraction between their atoms.
Iodine, Bromine, Chlorine
Bromine, Iodine, Chlorine
Iodine, Chlorine, Bromine
Bromine, Chlorine, Iodine
The correct option is A: Iodine, Bromine, Chlorine
The order is determined by the force of attraction between the atoms:
Iodine (volatile solid): In this state, particles are tightly packed, indicating the highest force of attraction.
Bromine (brown liquid): Here, molecules have moderate freedom to move, implying lesser attraction compared to solids but more than gases.
Chlorine (greenish yellow gas): The molecules move freely in any direction, showing the lowest force of attraction.
Thus, the correct decreasing order of elements in terms of the force of attraction between their atoms is:
Iodine (solid) > Bromine (liquid) > Chlorine (gas)
Which of the following is most soluble in water?
A. $Ba_3(PO_4)_2 (K_{sp} = 6 \times 10^{-39})$_
B. $ZnS (K_{sp} = 7 \times 10^{-16})$
C. $Fe(OH)_3 (K_{sp} = 6 \times 10^{-38})$_
D. $Ag_3(PO_4) (K_{sp} = 1.8 \times 10^{-18})$
To determine which compound is the most soluble in water, we need to compare the solubility product constants ($ K_{sp} $) for each compound. The compound with the highest $ K_{sp} $ will be the most soluble.
Given the $ K_{sp} $ values are:
For $ \text{Ba}_{3}( \text{PO}_{4})_{2} $: $ 6 \times 10^{-39} $
For $ \text{ZnS} $: $ 7 \times 10^{-16} $
For $ \text{Fe}(\text{OH})_{3} $: $ 6 \times 10^{-38} $
For $ \text{Ag}_{3}( \text{PO}_{4}) $: $ 1.8 \times 10^{-18} $
Comparing these values, $ \text{ZnS} $ has the highest $ K_{sp} $ of $ 7 \times 10^{-16} $. Thus, $ \text{ZnS} $ is the most soluble compound in water among the given options.
Correct Answer: B
So, the correct answer is: $$ \text{ZnS} \left( K_{sp} = 7 \times 10^{-16} \right) $$
Final Answer: B