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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Anand pratap singh
A is correct One unit cell of NaCl contains 4 units of NaCl. Wt of one unit cell will be.... 4×58.5/6.023×10^23 gm Now 4×58.5/6.023×10^23 gm... Contains 1 unit cell. So 1 gm will contain... 6.023×10^23/4×58.5 =2.57×10^21 unit cells.