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A : All crystals of same substance posse...

A : All crystals of same substance possess the same elements of symmetry.
R : The size of crystal of same substance may vary depending upon the conditions of crystallisation.

A

If both Assertion & Reason are true and the reason is the correct explanation of the assertion .

B

If both Assertion & Reason are true but the reason is not the correct explanation of the assertion .

C

If Assertion is true statement but Reason is false .

D

If both Assertion and Reason are false statements.

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The correct Answer is:
To solve the assertion and reason question, we will analyze both statements step by step. ### Step 1: Analyze the Assertion **Assertion (A)**: All crystals of the same substance possess the same elements of symmetry. - **Explanation**: The assertion refers to the concept of symmetry in crystals. According to the law of constancy of symmetry, all crystals of a particular substance will have the same elements of symmetry, which include: - Plane of Symmetry (POS) - Center of Symmetry (COS) - Axis of Symmetry (AOS) Since this law holds true for all crystals of the same substance, we conclude that the assertion is **true**. ### Step 2: Analyze the Reason **Reason (R)**: The size of the crystal of the same substance may vary depending upon the conditions of crystallization. - **Explanation**: This statement discusses how the size of crystals can change based on various factors such as temperature, pressure, pH, and purity of the solution during crystallization. This is a true statement as the size of crystals can indeed vary under different crystallization conditions. ### Step 3: Determine the Relationship Between A and R - While both the assertion and reason are true statements, they address different aspects of crystallization. The assertion focuses on symmetry, while the reason discusses the size of crystals. ### Conclusion Since both the assertion and reason are true, but the reason does not explain the assertion, the correct answer is: **Option 2**: Both assertion and reason are true, but reason is not the correct explanation of assertion. ---
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AAKASH INSTITUTE ENGLISH-THE SOLID STATE -Assignment (SECTION - D) (ASSERTION-REASON TYPE QUESTION)
  1. A : In NaCl structure, the interionic distance is a/2 (a = Unit cell e...

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  2. A : The co - ordination number of CaF(2) is 8 : 4. R : Ca^(2+) ion...

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  3. A : The number of spheres are equal to the number of octahedral voids ...

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  4. A : In Schottky defect, density of crystal decreases. R : Equal nu...

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  5. A : If a tetrad axis is passed through the unit cell of NaCl and all i...

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  6. A : A particle at the corner of CCP unit cell has (1)/(8)th of its con...

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  7. A : Glass belongs to the category of covalent network solid. R : U...

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  8. A : NaCl shows Schottky defect at room temperature. R : NaCl shows...

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  9. A : Fe(3)O(4) is ferrimagnetic at room temperature but becomes paramag...

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  10. A : In molecular solids the lattice points are occupied by the atoms o...

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  11. A : Silicon is insulator at 0 K but semiconductor at room temperature....

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  12. A : Amorphous solids are isotropic. R : Amorphous solids are not rig...

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  13. A : In NaCl coordination number of Cl^(-) ion is 6 but in CsCl coordin...

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  14. A : All crystals of same substance possess the same elements of symmet...

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  15. A : AgBr shows both Schottky and Frenkel defect. R : AgBr is a cry...

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  16. A : Number of carbon atoms per unit cell in diamond is 8. R : The ...

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  17. A : The coordination number of ionic compound depends upon radius rati...

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  18. A : Number of rectangular plane in a cubic crystal is 3. R : Recta...

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  19. A : ccp is more efficient than hcp. R : Packing fraction is differe...

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  20. A : Coordination number of both Na^(+) and Cl^(-) NaCl is 6. R : Se...

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