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How will you distinguish between the following pairs of terms : (i) Hexagonal close-packing and cubic close-packing ? (ii) Crystal lattice and unit cell ? (iii) Tetrahedral void and octahedral void ? |
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Answer» Solution :(i) ABAB ………….. type packing is CALLED hexagonal close-packing while ABCABC …………….. type packing is called cubic close-packing. (ii) Regular ARRANGEMENT of particles of a crystal in a three-dimensional space is called crystal lattice. Smallest three dimensional PORTION of a crystal lattice which when repeated over and again in the three dimensions produces the COMPLETE crystal lattice, is called unit cell. (iii) A void surrounded by four spheres is called TETRAHEDRAL void whereas a void surrounded by six spheres is called octahedral void. |
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