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QUESTION
Q58) If NA is Avogadro's number then number of valence electron is 4.2g of nitride ions(N3-)is .. [ CBSE PMT 1994]




SOLUTION

Atomic weight of nitrogen is 14 = 1 mole
4.2g = 4.2/14 mole
Now number of valance electron in N-3 =5+3 =8

Therefore number of electrons in (4.2/14) moles of nitrogen ion =
(4.2/14) 8 = 2.4 moles or 4.2 N

Answer: (a)