Chemistry-1999-Set III

Q 2 In the rock salt structure how many Na+ ions occupy second-nearest neighbour location of a Na+ ion?
Ans. 1 12

Q 3 Which type of hybridisation explains the trigonal bipyramidal shape of SF4 ?
Ans. 2 sp3d

Q 11 Calculate the uncertainity in te velocity of a wagon of mass 3000 kg whose position is known to an accuracy of 10pm. (h = 6.63 x 10-34.Js)
Ans. 3 x.mv > h/ 4
v = h / 4pmv = 6.6 x 1034 / 4 x 3.14 x 3000 x 10 x 10-12.
= 1.75 x 10 -27 ms-1

Q 12(i) What is the basic building unit of all silicates?
(ii) How many oxygen atom of this unit are shared with others in the silicate ion Si3O96- ion?

Ans. 4 (i) SiO4
(ii) 2

Q 23 Draw the structure and write the hybridisation state of the central atom of each of the following species :
(i) [Co(NH3)6]3+
(ii) [NiCl4)]2-)

Ans. 5 (i) d2sp3 structural – octahedral
(ii) sp3 structural – tetrahedarl

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