Colloids that cannot be easily coagulated are...
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Stability β Size and intermolecular forces.
Macromolecular colloids are stable due to their large size and intermolecular forces.
Stability of macromolecular colloids prevents easy coagulation.
Final result: Macromolecular colloids cannot be easily coagulated.
Confusing stability of colloids based on types.
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Relate stability of colloids to their molecular structures.
Stability β Size and intermolecular forces.
Macromolecular colloids are stable due to their large size and intermolecular forces.
Stability of macromolecular colloids prevents easy coagulation.
Final result: Macromolecular colloids cannot be easily coagulated.
Confusing stability of colloids based on types.
The electrolyte having maximum flocculation value for AgI/AgβΊ sol. is...
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Flocculation value β 1/(charge).
Flocculation value is inversely proportional to coagulating power.
NaCl has the lowest charge (minimum coagulating power) and hence the highest flocculation value.
Final result: Maximum flocculation value = NaCl.
Confusing coagulating power with flocculation value directly.
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Relate charge of ions to flocculation and coagulating power.
Flocculation value β 1/(charge).
Flocculation value is inversely proportional to coagulating power.
NaCl has the lowest charge (minimum coagulating power) and hence the highest flocculation value.
Final result: Maximum flocculation value = NaCl.
Confusing coagulating power with flocculation value directly.
Sodium metal crystallizes in B.C.C. lattice with edge length = 4.29 Γ . Radius of sodium atom is...
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r = 0.433 x edge length
Radius in BCC: r = 0.433a; a = 4.29 Γ .
Calculate r = 0.433 x 4.29 = 1.857 Γ .
Final result: Radius = 1.857 Γ .
Miscomputing radius by using incorrect lattice constant.
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Carefully compute radius using BCC lattice formula.
r = 0.433 x edge length
Radius in BCC: r = 0.433a; a = 4.29 Γ .
Calculate r = 0.433 x 4.29 = 1.857 Γ .
Final result: Radius = 1.857 Γ .
Miscomputing radius by using incorrect lattice constant.
Process responsible for delta formation where rivers meet sea is
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Colloid + electrolyte
Consider particle behavior
Check electrolyte effect
Identify process
Process identification
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Salt causes coagulation
Colloid + electrolyte
Consider particle behavior
Check electrolyte effect
Identify process
Process identification
The unit cell with crystallographic dimensions, a β b β c, Ξ± = Ξ³ = 90Β° and Ξ² β 90Β° is...
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Monoclinic: a β b β c, Ξ± = Ξ³ = 90Β°, Ξ² β 90Β°.
Crystallographic dimensions and angles suggest a monoclinic unit cell.
Confirm a β b β c, Ξ± = Ξ³ = 90Β°, Ξ² β 90Β° corresponds to monoclinic system.
Final result: Unit cell is monoclinic.
Misinterpreting parameters as orthorhombic or tetragonal.
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Carefully match crystallographic parameters to crystal systems.
Monoclinic: a β b β c, Ξ± = Ξ³ = 90Β°, Ξ² β 90Β°.
Crystallographic dimensions and angles suggest a monoclinic unit cell.
Confirm a β b β c, Ξ± = Ξ³ = 90Β°, Ξ² β 90Β° corresponds to monoclinic system.
Final result: Unit cell is monoclinic.
Misinterpreting parameters as orthorhombic or tetragonal.
Schottky defect in a crystal is observed when
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None required
Define Schottky defect
Note requirement for electrical neutrality
Confirm equal missing ions
Confusing with Frenkel defect
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Think about charge balance
None required
Define Schottky defect
Note requirement for electrical neutrality
Confirm equal missing ions
Confusing with Frenkel defect
Which is not favorable for physical adsorption?
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ΞH < 0 (exothermic)
Consider exothermic nature
Check Le Chatelier's
Identify unfavorable
Temperature effect
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Heat opposes adsorption
ΞH < 0 (exothermic)
Consider exothermic nature
Check Le Chatelier's
Identify unfavorable
Temperature effect
Correct statement about defect in solids is
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Frenkel defect equation
Compare defects
Check characteristics
Identify correct
Defect types
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Cation displacement
Frenkel defect equation
Compare defects
Check characteristics
Identify correct
Defect types
In a face centered cubic arrangement of A and B atoms in which 'A' atoms are at the corners of the unit cell and 'B' atoms are at the face centers, one of the 'A' atoms is missing from one corner in the unit cell. The simplest formula of the compound is
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AβBββ
For A: 7 corners Γ 1/8 = 7/8
For B: 6 faces Γ 1/2 = 3
Ratio A:B = 7/8:3 = 7:24
Corner/face contribution calculation
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Count contributions
AβBββ
For A: 7 corners Γ 1/8 = 7/8
For B: 6 faces Γ 1/2 = 3
Ratio A:B = 7/8:3 = 7:24
Corner/face contribution calculation
Gold sol is not a
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Au + reducing agent β Au sol
Identify colloid type
Check particle size
Consider formation
Confusion between different types of sols
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Gold forms multimolecular colloid
Au + reducing agent β Au sol
Identify colloid type
Check particle size
Consider formation
Confusion between different types of sols
Which crystal has unit cells with aβ bβ c and Ξ±β Ξ²β 90Β°?
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aβ bβ c, Ξ±β Ξ²β Ξ³β 90Β°
Check crystal systems
Compare parameters
Identify triclinic
Crystal systems
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Triclinic system
aβ bβ c, Ξ±β Ξ²β Ξ³β 90Β°
Check crystal systems
Compare parameters
Identify triclinic
Crystal systems
Edge length of a cube is 300 pm. Its body diagonal would be
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d = aβ3 where a = edge length
Apply Pythagorean theorem
Consider cubic structure
Calculate diagonal
Students forget β3 factor
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Body diagonal = aβ3
d = aβ3 where a = edge length
Apply Pythagorean theorem
Consider cubic structure
Calculate diagonal
Students forget β3 factor
In F.C.C. the cell is shared equally by how many unit cells?
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Face atoms = 6, sharing = 1/2
Count face atoms
Calculate sharing
Apply crystal rules
Students forget partial sharing of atoms
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Each face atom shared by 2 cells
Face atoms = 6, sharing = 1/2
Count face atoms
Calculate sharing
Apply crystal rules
Students forget partial sharing of atoms
Which of the following electrolytes will have maximum coagulating value for AgI/AgβΊ sol?
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1/coagulating power β zβΆ
Compare ion charges
Consider Schulze-Hardy rule
Evaluate coagulating power
Confusion between charge and coagulating power
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Lower charge = higher value
1/coagulating power β zβΆ
Compare ion charges
Consider Schulze-Hardy rule
Evaluate coagulating power
Confusion between charge and coagulating power
1 mole NaCl doped with 10β»β΅ mole SrClβ. Number of cationic vacancies in crystal lattice
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Vacancies = NA Γ moles of SrΒ²βΊ
Write substitution equation
Calculate vacancies per SrΒ²βΊ
Multiply by Avogadro number
Not considering charge balance
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One SrΒ²βΊ creates one vacancy
Vacancies = NA Γ moles of SrΒ²βΊ
Write substitution equation
Calculate vacancies per SrΒ²βΊ
Multiply by Avogadro number
Not considering charge balance
Number of atoms in 2.4g of BCC crystal with edge length 200pm is (density=10g/cmΒ³, NA=6Γ10Β²Β³)
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n = mNA/M
Calculate volume and mass
Find number of atoms per unit cell
Convert to total atoms
Not considering atoms per unit cell
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Use density and atomic mass
n = mNA/M
Calculate volume and mass
Find number of atoms per unit cell
Convert to total atoms
Not considering atoms per unit cell
Which is a network crystalline solid?
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Al-N-Al-N network
Check bonding type
Verify 3D network
Confirm covalent network
Confusing ionic with network solids
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Look for extended covalent bonds
Al-N-Al-N network
Check bonding type
Verify 3D network
Confirm covalent network
Confusing ionic with network solids
Which cleansing agent gets precipitated in hard water?
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CββHββ COONa + CaΒ²βΊ β (CββHββ COO)βCaβ
Consider reaction of cleansing agents with CaΒ²βΊ/MgΒ²βΊ ions
Sodium stearate forms insoluble calcium/magnesium stearate
Soap (sodium stearate) forms precipitate with hard water ions
Students often don't consider the ionic nature of soap-hard water interaction
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Think about traditional soap behavior in hard water
CββHββ COONa + CaΒ²βΊ β (CββHββ COO)βCaβ
Consider reaction of cleansing agents with CaΒ²βΊ/MgΒ²βΊ ions
Sodium stearate forms insoluble calcium/magnesium stearate
Soap (sodium stearate) forms precipitate with hard water ions
Students often don't consider the ionic nature of soap-hard water interaction
Critical Micelle Concentration for soap solution is 1.5Γ10β»β΄ mol Lβ»ΒΉ. Micelle formation possible when concentration in mol Lβ»ΒΉ is
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[Soap] > CMC for micelles
Compare with CMC
Check concentration
Verify micelle formation
Not comparing with CMC value
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Concentration must exceed CMC
[Soap] > CMC for micelles
Compare with CMC
Check concentration
Verify micelle formation
Not comparing with CMC value
During adsorption of a gas on a solid
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ΞG = ΞH - TΞS
Check spontaneity
Analyze enthalpy change
Consider entropy change
Thermodynamic parameters
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Spontaneous process with decreased randomness
ΞG = ΞH - TΞS
Check spontaneity
Analyze enthalpy change
Consider entropy change
Thermodynamic parameters
When a sol of AgI is prepared by mixing equal volumes of 0.1M AgNOβ and 0.2M KI, which statement is correct?
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None
Check concentrations
Identify excess ions
Determine adsorption
Colloidal properties
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Excess Iβ» forms negative sol
None
Check concentrations
Identify excess ions
Determine adsorption
Colloidal properties
When silicon is doped with gallium, it forms
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None
Compare valence electrons
Check hole formation
Identify type
Semiconductor types
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Ga has fewer valence electrons
None
Compare valence electrons
Check hole formation
Identify type
Semiconductor types
A metal crystallises in face centred cubic structure with metallic radius β2Γ . The volume of the unit cell (in mΒ³) is
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V = aΒ³, a = 4r/β2
Calculate edge length
Find unit cell volume
Convert units
Unit cell calculations
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Use FCC formula
V = aΒ³, a = 4r/β2
Calculate edge length
Find unit cell volume
Convert units
Unit cell calculations
A metal exists as an oxide with formula Mβ.ββO. Metal M can exist as MΒ²βΊ and MΒ³βΊ in its oxide Mβ.ββO. The percentage of MΒ³βΊ in the oxide is nearly
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MΒ²βΊ + MΒ³βΊ total charge = OΒ²β» charge
Balance charges
Calculate ion ratio
Find percentage
Oxidation states
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Use charge neutrality
MΒ²βΊ + MΒ³βΊ total charge = OΒ²β» charge
Balance charges
Calculate ion ratio
Find percentage
Oxidation states
Which can adsorb larger amount of hydrogen gas?
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Adsorption β Surface Area
Compare surface area of different adsorbents
Consider metallic nature and surface activity
Palladium has highest Hβ adsorption capacity
Confusing physical and chemical adsorption
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Surface area and nature of metal affect adsorption
Adsorption β Surface Area
Compare surface area of different adsorbents
Consider metallic nature and surface activity
Palladium has highest Hβ adsorption capacity
Confusing physical and chemical adsorption
Which of the following is NOT true about the amorphous solids?
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Amorphous vs Crystalline properties
Compare properties
Identify incorrect statement
Amorphous solids are isotropic
Confusing isotropic and anisotropic
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Properties same in all directions
Amorphous vs Crystalline properties
Compare properties
Identify incorrect statement
Amorphous solids are isotropic
Confusing isotropic and anisotropic
Alkali halides do not show dislocation defect because
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Frenkel defect requirements
Consider ionic sizes
Understand Frenkel defect
Size difference prevents movement
Confusing different defect types
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Large size difference prevents defect
Frenkel defect requirements
Consider ionic sizes
Understand Frenkel defect
Size difference prevents movement
Confusing different defect types
How many number of atoms are there in a cube based unit cell, having one atom on each corner and 2 atom on each body diagonal of cube?
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Total = (8Γ1/8) + 3Γ2 = 7
Count corner atoms
Add body diagonal atoms
Consider shared atoms
Forgetting to count shared atoms
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Corner atoms contribute 1/8th
Total = (8Γ1/8) + 3Γ2 = 7
Count corner atoms
Add body diagonal atoms
Consider shared atoms
Forgetting to count shared atoms
Vacant space in body centered cubic lattice unit cell is about
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% vacant space = 100 - % packing efficiency
Calculate volume of atoms
Compare with unit cell volume
Calculate percentage space
Confusing different lattice types
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Packing efficiency = 68%
% vacant space = 100 - % packing efficiency
Calculate volume of atoms
Compare with unit cell volume
Calculate percentage space
Confusing different lattice types
A metal crystallises in a body centered cubic lattice with metallic radius β3Γ . The volume of unit cell in mΒ³ is
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V = aΒ³
Calculate edge length
Find volume
Convert units
Unit conversion confusion
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a = 4r/β3
V = aΒ³
Calculate edge length
Find volume
Convert units
Unit conversion confusion
Colloidal solution commonly used in the treatment of skin disease is
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N/A
Identify medical applications of colloids
Sulphur has antiseptic properties
Colloidal sulphur is used in dermatology
Confusing different colloidal solutions' applications
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Colloidal solutions have medicinal applications
N/A
Identify medical applications of colloids
Sulphur has antiseptic properties
Colloidal sulphur is used in dermatology
Confusing different colloidal solutions' applications
Match Column A (type of crystalline solid) with Column B (example): P.Molecular Solid-i.SiC, Q.Ionic Solid-ii.Mg, R.Metallic Solid-iii.HβO, S.Network Solid-iv.MgO
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Types of solids
Identify solid type
Match examples
Verify properties
Property classification confusion
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Consider bonding type
Types of solids
Identify solid type
Match examples
Verify properties
Property classification confusion
If 'a' stands for edge length of cubic systems - The ratio of radii in simple cubic, body centered cubic and face centered cubic unit cells is
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r(sc):r(bcc):r(fcc)
Compare structures
Calculate radii
Find ratio
Radius ratio confusion
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r = fΓa
r(sc):r(bcc):r(fcc)
Compare structures
Calculate radii
Find ratio
Radius ratio confusion
For Freundlich isotherm, graph of log(x/m) vs log(P) slope and intercept are
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log(x/m) = 1/n log P + log K
Write Freundlich equation
Take log both sides
Identify slope-intercept
Confusion in log forms
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Use y=mx+c form
log(x/m) = 1/n log P + log K
Write Freundlich equation
Take log both sides
Identify slope-intercept
Confusion in log forms
In raw sugar decolorization with animal charcoal, identify correct terminology
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Physical Adsorption
Identify adsorbent
Identify adsorbate
Identify process
Confusion between adsorption/absorption
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Surface phenomenon
Physical Adsorption
Identify adsorbent
Identify adsorbate
Identify process
Confusion between adsorption/absorption
Which one of the following is a cationic detergent?
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No specific formula.
Cetyltrimethylammonium bromide is a cationic detergent due to its positively charged quaternary ammonium group.
Other options are anionic detergents or non-detergent molecules.
Final result: Cationic detergent is Cetyltrimethylammonium bromide.
Confusing cationic detergents with anionic or neutral compounds.
π’ Uh oh! Incorrect answer, Try again
Relate cationic detergents to their functional groups.
No specific formula.
Cetyltrimethylammonium bromide is a cationic detergent due to its positively charged quaternary ammonium group.
Other options are anionic detergents or non-detergent molecules.
Final result: Cationic detergent is Cetyltrimethylammonium bromide.
Confusing cationic detergents with anionic or neutral compounds.
Which of the following crystals has the unit cell such that a = b β c and Ξ± = Ξ² = 90Β°, Ξ³ = 120Β°?
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No formula involved.
The unit cell described corresponds to a hexagonal lattice structure.
Graphite has a layered hexagonal structure, meeting the given conditions.
Graphite satisfies a = b β c and Ξ± = Ξ² = 90Β°, Ξ³ = 120Β°.
Confusing between unit cell parameters for hexagonal and tetragonal structures.
π’ Uh oh! Incorrect answer, Try again
Recall the geometry of different crystal lattices.
No formula involved.
The unit cell described corresponds to a hexagonal lattice structure.
Graphite has a layered hexagonal structure, meeting the given conditions.
Graphite satisfies a = b β c and Ξ± = Ξ² = 90Β°, Ξ³ = 120Β°.
Confusing between unit cell parameters for hexagonal and tetragonal structures.
For the coagulation of positively charged ferric oxide sol, flocculating power order is:
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Flocculation β ion charge.
Flocculating power is proportional to the charge of ions (Schulze-Hardy rule).
High-charge ions (e.g., [Fe(CN)β]Β³β») exhibit greater coagulating power than low-charge ions.
Final Answer: Option B is correct.
Overlooking the impact of ion charge on coagulation.
π’ Uh oh! Incorrect answer, Try again
Recall the relationship between charge and coagulation.
Flocculation β ion charge.
Flocculating power is proportional to the charge of ions (Schulze-Hardy rule).
High-charge ions (e.g., [Fe(CN)β]Β³β») exhibit greater coagulating power than low-charge ions.
Final Answer: Option B is correct.
Overlooking the impact of ion charge on coagulation.
MnO exhibits:
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No formula involved.
MnO exhibits antiferromagnetism due to its arrangement of magnetic moments in opposite directions.
Magnetic moments in MnO cancel out, resulting in no net magnetic moment.
Final conclusion: MnO is antiferromagnetic.
Assuming MnO has paramagnetic properties like Mn ions.
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Recall magnetic properties and arrangements of magnetic moments.
No formula involved.
MnO exhibits antiferromagnetism due to its arrangement of magnetic moments in opposite directions.
Magnetic moments in MnO cancel out, resulting in no net magnetic moment.
Final conclusion: MnO is antiferromagnetic.
Assuming MnO has paramagnetic properties like Mn ions.
The number of atoms in 4.5 g of a face-centred cubic crystal with edge length 300 pm is...
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d = (Z Γ M) / (Na Γ aΒ³).
Use the formula d = (Z Γ M) / (Na Γ aΒ³) to find the density of the unit cell.
Substituting values: d = 10, a = 300 pm, Na = 6.022 Γ 10^23, Z = 4, M = 40.5 g/mol.
Result: Number of atoms = 6.6 Γ 10^22.
Miscalculating Z or misinterpreting the given edge length (pm to cm).
π’ Uh oh! Incorrect answer, Try again
Focus on unit cell dimensions and atomic packing.
d = (Z Γ M) / (Na Γ aΒ³).
Use the formula d = (Z Γ M) / (Na Γ aΒ³) to find the density of the unit cell.
Substituting values: d = 10, a = 300 pm, Na = 6.022 Γ 10^23, Z = 4, M = 40.5 g/mol.
Result: Number of atoms = 6.6 Γ 10^22.
Miscalculating Z or misinterpreting the given edge length (pm to cm).
Identify the incorrect statement regarding colloidal solutions:
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No formula involved.
Brownian movement is caused by unbalanced molecular bombardment.
Correct the misunderstanding about balanced versus unbalanced forces in colloids.
Final Answer: Brownian movement is unbalanced, not balanced.
Confusing the reason for Brownian motion (balanced vs. unbalanced forces).
π’ Uh oh! Incorrect answer, Try again
Review molecular behavior in colloids.
No formula involved.
Brownian movement is caused by unbalanced molecular bombardment.
Correct the misunderstanding about balanced versus unbalanced forces in colloids.
Final Answer: Brownian movement is unbalanced, not balanced.
Confusing the reason for Brownian motion (balanced vs. unbalanced forces).