15 extra multiple-choice questions for Solid State (12th Standard Chemistry, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Which of the following properties is not a general characteristic of the solid state of matter?
- A. Definite volume and shape
- B. High incompressibility
- C. Strong cohesive forces
- D. High fluidity and diffusionCorrect
Explanation. Solids are characterized by strong attractive forces that keep particles in fixed positions, making them rigid and preventing the fluidity typically observed in liquids or gases.
Q2
What distinguishes an amorphous solid from a crystalline solid?
- A. Presence of a long-range orderly arrangement
- B. A sharp and definite melting point
- C. Short-range, random arrangement of constituentsCorrect
- D. Anisotropic physical properties
Explanation. Amorphous solids lack the long-range periodic order found in crystals. Their particles are randomly arranged, leading to isotropic properties and a range of softening temperatures.
Q3
Under which condition do ionic solids like sodium chloride conduct electricity?
- A. In the solid state at room temperature
- B. When they are in molten state or dissolved in waterCorrect
- C. When subjected to very high pressure
- D. Only when they are absolute zero temperature
Explanation. In solid form, ions are fixed in lattice positions and cannot move. Melting or dissolving releases these ions, allowing them to move freely and conduct an electric current.
Q4
Which type of crystalline solid is held together by a three-dimensional network of covalent bonds?
- A. Molecular crystals
- B. Ionic crystals
- C. Covalent network crystalsCorrect
- D. Metallic crystals
Explanation. Covalent solids, such as diamond or silicon carbide, consist of atoms linked entirely by covalent bonds in a continuous network, making them extremely hard with high melting points.
Q5
Solid carbon dioxide (dry ice) is classified as which type of molecular solid?
- A. Non-polar molecular solid
- B. Polar molecular solidCorrect
- C. Hydrogen bonded molecular solid
- D. Metallic molecular solid
Explanation. Molecules formed by polar covalent bonds, like CO2 in its solid form, are held by dipole-dipole interactions, classifying them as polar molecular solids.
Q6
The characteristic lustre and high electrical conductivity of metals are primarily due to the presence of:
- A. Strong ionic bonds
- B. Weak van der Waals forces
- C. Mobile electrons pervading the spaceCorrect
- D. Localized covalent sharing
Explanation. Metallic solids consist of positive ions in a sea of mobile electrons. These free electrons are responsible for reflecting light and carrying thermal or electrical energy.
Q7
Based on the crystal lattice systems, how many total possible Bravais lattices exist in three dimensions?
- A. 7
- B. 14Correct
- C. 21
- D. 32
Explanation. While there are seven basic crystal systems, variations in how points are centered within these systems result in exactly fourteen distinct types of space lattices, known as Bravais lattices.
Q8
In a simple cubic unit cell, what is the coordination number of each atom?
- A. 4
- B. 6Correct
- C. 8
- D. 12
Explanation. In a simple cubic arrangement, every atom is in direct contact with six immediate neighbors: four in its own horizontal plane, one above, and one below.
Q9
What is the total number of atoms present per unit cell in a Body Centered Cubic (BCC) structure?
- A. 1
- B. 2Correct
- C. 3
- D. 4
Explanation. A BCC unit cell contains eight atoms at the corners, each contributing 1/8, and one full atom at the center. This results in a total of 1 + 1 = 2 atoms.
Q10
Which type of three-dimensional close packing is represented by the 'abcabc' repeating pattern?
- A. Hexagonal close packing (hcp)
- B. Simple cubic packing (sc)
- C. Cubic close packing (ccp)Correct
- D. Body centered cubic packing (bcc)
Explanation. The 'abc' arrangement occurs when the third layer is placed differently from the first two, creating a face-centered cubic or cubic close packed structure.
Q11
Which of the following metals is unique for crystallizing in a simple cubic pattern?
- A. Sodium
- B. Iron
- C. PoloniumCorrect
- D. Copper
Explanation. Among all known metals in the periodic table, polonium is the only element that forms a simple cubic crystal structure under standard conditions.
Q12
How does the presence of a Schottky defect affect the density of a crystal?
- A. It increases the density
- B. It decreases the densityCorrect
- C. It has no effect on density
- D. It first increases then decreases density
Explanation. A Schottky defect involves missing pairs of cations and anions from the lattice. Since mass is lost while volume remains nearly constant, the overall density of the crystal decreases.
Q13
Which statement correctly describes a Frenkel defect?
- A. Equal numbers of cations and anions are missing
- B. An ion moves from its lattice site to an interstitial positionCorrect
- C. Extra metal ions occupy the interstitial holes
- D. Impurity atoms replace the original lattice atoms
Explanation. In a Frenkel defect, an ion is dislocated from its normal lattice position and occupies a small void or interstitial site. This typically occurs when ions differ significantly in size.
Q14
The change in colour of zinc oxide from colourless to yellow upon heating is an example of which defect?
- A. Schottky defect
- B. Metal deficiency defect
- C. Metal excess defectCorrect
- D. Frenkel defect
Explanation. Heating ZnO causes it to lose oxygen, leaving excess zinc ions and electrons in interstitial positions. These electrons absorb light, creating the yellow colour observed in the material.
Q15
F-centers in a crystal lattice are responsible for which physical property?
- A. Increased mechanical strength
- B. Enhanced electrical insulation
- C. The appearance of colour in the crystalCorrect
- D. Perfect stoichiometric balance
Explanation. F-centers are anionic vacancies occupied by unpaired electrons. The excitation of these trapped electrons by light energy imparts characteristic colours to otherwise colourless ionic crystals.
Frequently asked questions
How many MCQs are there in Solid State?
This chapter has 15 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 12th Standard Chemistry MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Solid State book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
