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Why the melting points of NaF and MgO (9...

Why the melting points of `NaF` and `MgO` `(990^(@)C` and `2640^(@)C`) are so different although both have same number of electrons and nearly the same internuclear distance (236 pm and 216 pm)?

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`MgO` is a bi-bivalent `(+2, -2)` compound whereas `NaF` is a uni-univalent `(+1, -1)`, compound. Hence, force of electrostatic attraction in `MgO` is stronger.
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CENGAGE CHEMISTRY-NCERT BASED EXERCISE-Short Answer Type Questions
  1. Why do some substance exist as solids?

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  2. Why do the window glass of old old building (a) look milky and (b) bec...

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  3. Why the melting points of NaF and MgO (990^(@)C and 2640^(@)C) are so ...

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  4. How many types of centred unit cells exist?

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  5. How many types of two-dimensional lattice exist? Why pentagonal lattic...

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  6. How many TVs and OV s occur per unit cell and per atom in a closest pa...

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  7. Where the TVs and OV s are located in a closet packed structure?

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  8. What is the distance between two TVs?

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  9. In an hcp structure, calculate a. Z("eff) Base area of hexagon c...

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  10. In a diamond cubic (dc) structure, calculate (a) Z("eff")(b) CN radi...

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  11. What is the ratio of (TV//OV)("occupied") in spinel an inverse spinel...

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  12. What is the CN of cation and anion in a corundum structure?

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  13. What is the occurrence of different forms of the same compound called?

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  14. How many types of allotropy exist?

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  15. How can a substance be made amorphous?

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  16. Why does ZnO show increased electrical conductivity and turns yellow o...

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  17. Why NiO and FeO are nonstroichiometric with the formula Ni(0.98)O and ...

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  18. Why the defectsof the crystalline solids are called thermodynamic defe...

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  19. Why stoichiometric defects are also called intrinsic defects?

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  20. Give the name of one solid which shows both Schottky and Frenkel defec...

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