Chemistry-1999-Set II

Q 1 Write the number of unpaired electron(s) in an atom of an element with the atomic number 21.
Ans. 1 1

Q 3 How many atoms are there in a unit cell of a metal crystallising in fcc structure?
Ans. 2 4

Q 9 In the formula Fe(h5 – (C5H5)2 what does the prefix ‘h5′ denote.
Ans. h5 – indicate that there are 5 carbon atoms bound to the metal in the compound.

Q 21 For the first row of transition metals the Eo values are :
V Cr Mn Fe Co Ni Cu
Eo(M2+/M) -1.18 -0.91 -1.18 -0.44 -0.28 -0.25 +0.34V

Give suitable explanation for the irregular trend in these values.

Ans. Due to irregular trend in their I.E. values/heat of sublimation/heat as hydration.

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