All India Engineering / Architecture Entrance Examination (AIEEE)

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AIEEE 2008 Chemistry

Q. 26. Larger number of oxidation states are exhibited by the actinoids than those by lanthanoids, the main reason being

1. more energy difference between 5f and 6d than between 4f and 5d orbitals.
2. more reactive nature of the actinoids than the lanthanoids.
3. 4f orbitals more diffused than the 5f orbitals.
4. lesser energy difference between 5f and 6d than between 4f and 5d orbitals.

Sol: The energy difference between 5 f and 6d is very less than that between 4f and 5d orbitals. Therefore, in actinoids, the electron can be removed from 5f and 6d both. So, they exhibit more number of oridation state.

Q. 27. In a compound, atoms of element Y form ccp lattice and those of element X occupy 2/3^rd of tetrahedral voids. The formula of the compound will be

1. X₂Y
2. X₃Y₄
3. X₄Y₃
4. X₂Y₃

Sol:

Q. 28. Gold numbers of protective colloids (A), (B), (C) and (D) are 0.50, 0.01, 0.10 and 0.005, respectively. The correct order of their protective powers is

1. (A) < (C) < (B) < (D)
2. (B) < (D) < (A) < (C)
3. (D) < (A) < (C) < (B)
4. (C) < (B) < (D) < (A)

Sol: If the gold number of a protective coil is less then its protective power is good.

0.005 < 0.01 < 0.10 < 0.50

or, (A) < (C) < (B) < (D)

Q. 29. The vapour pressure of water at 20⁰C is 17.5 mm Hg. If 18 g of glucose (C₆H1₂O₆) is added to 178.2 g of water at 20⁰C, the vapour pressure of the resulting solution will be

1. 16.500 mm Hg
2. 17.325 mm Hg
3. 17.675 mm Hg
4. 15.750 mm Hg

Sol: