Solid State Class 12 Chapter 1 MCQs Maharashtra Board

Q1. Choose the most correct answer.

Q1. Molecular solids are…………
a. crystalline solids
b. amorphous solids
c. ionic solids
d. metallic solids
Answer: A) crystalline solids
Explanation: Molecular solids consist of molecules held together by intermolecular forces (like hydrogen bonding, van der Waals forces, etc.) arranged in a definite crystal lattice, making them crystalline solids.

Chapter 2: Solutions

Q2. Which of the follwong is n-type semiconductor?
a. Pure Si
b. Si doped with As
c. Si doped with Ga
d. Ge doped with In
Answer: b) Si doped with As
Explanation: n-type semiconductors are created by doping a semiconductor (like silicon) with a pentavalent impurity (such as arsenic). This adds extra electrons, making it an n-type (negative) semiconductor.

Chapter 3: Ionic Equilibrium 

Q3. In Frenkel defect
a. electrical neutrality of the substance is changed.
b. density of the substance is changed.
c. both cation and anion are missing
d. overall electical neutrality is preserved.
Answer: d) overall electrical neutrality is preserved.
Explanation: In a Frenkel defect, an ion (typically a cation) leaves its lattice site and occupies an interstitial site. This defect does not change the overall electrical neutrality or the density of the substance.

Chapter 4: Chemical Thermodynamics

Q4. In crystal lattice formed by bcc unit cell the void volume is
a. 68 %   
b. 74 % 
c.32 %   
d. 26 %
Answer: c) 32%
Explanation: In a body-centered cubic (bcc) lattice, the atoms occupy about 68% of the total volume, leaving 32% as void space.

Chapter 5: Electrochemistry

Q5. The coordination number of atoms in bcc crystal lattice is
a. 2.     
b. 4       
c. 6         
d. 8
Answer: d) 8
Explanation: In a body-centered cubic (bcc) lattice, each atom is surrounded by 8 nearest neighbors, giving it a coordination number of 8.

Chapter 6: Chemical Kinetics

Q6. Which of the following is not correct?
a.Four spheres are involved in the formation of tetrahedral void.
b. The centres of spheres in octahedral voids are at the apices of a regular tetrahedron.
c.If the number of atoms is N the number of octahedral voids is 2N.
d. If the number of atoms is N/2, the number of tetrahedral voids is N.
Answer: c) If the number of atoms is N the number of octahedral voids is 2N.
Explanation: In a close-packed structure, the number of octahedral voids is equal to the number of atoms (N), not 2N. The correct statement is if the number of atoms is N, the number of octahedral voids is N.

Chapter 7: Elements of Groups 16, 17 and 18 

Q7. A compound forms hcp structure. Number of octahedral and tetrhedral voids in 0.5 mole of substance is respectively.
a. 3.011×1023, 6.022×1023
b. 6.022×1023, 3.011×1023
c. 4.011×1023, 2.011×1023
d. 6.011×1023, 12.022×1023
Answer: a) 3.011×10²³, 6.022×10²³
Explanation: In a hexagonal close-packed (hcp) structure, there is one octahedral void per atom and two tetrahedral voids per atom. For 0.5 mole of substance (which is 0.5 × 6.022×10²³ atoms), the number of octahedral voids is 0.5 × 6.022×10²³ = 3.011×10²³, and the number of tetrahedral voids is 2 × 3.011×10²³ = 6.022×10²³.

Chapter 9: Coordination Compounds

Q8. Pb has fcc structure with edge length of unit cell 495 pm. Radius of Pb atom is
a. 205 pm
b. 185 pm
c. 260 pm
d. 175 pm
Answer: d) 175 pm