M.C.Q : Atomic Structure ( 1 to 1 0 )

LEVEL – I
1. If the electronic structure of oxygen atom is written as 1s2 2s2 2p4 it would violate

(A) Hund’s rule

(B) Paulis exclusion principle

(C) Both Hund’s and Pauli’s principles

(D) None of these

2. Number of nodal planes for f-orbital are

(A) 3

(B) 2

(C) 1

(D) 0

3. One Bohr magneton equals

(A) ehc /4π n

(B) e c /4hπ m

(C) hc /m e4π

(D) eh /4π m c

4. Three isotopes of an element have mass numbers M, (M + 1) and (M + 2). If the mean mass number is (M + 0.5) than which of the following ratio may be accepted for M , (M + 1) , (M + 2) in that order.

(A) 1 : 1 : 1

(B) 4 : 1 : 1

(C) 3 : 2 : 1

(D) 2 : 1 : 1

5. A possible set of quantum numbers for the last electron added to a gallium atom (Z = 31) in its ground state is

n    l   m   ms
(A) 4   1   –1   +1/2

(B) 4   0   0   –1/2

(C) 3   2   +2   +1/2

(D) 3   0   0   –1/2

6. The angle made by angular momentum vector of an electron with z axis is given by

(A) cosθ = l/m

(B) cosθ = √l/m

(C) cos θ = √[(l+1)/m ]

(D) cosθ = m/√l(l+1)

7. The distance between 3rd and 2nd orbit of hydrogen atom is

(A) 2.646 ×10–8 cm

(B) 2.116 ×10–8 cm

(C) 1.058 ×10–8 cm

(D) 0.529 × 10–8 cm

8. An atom has four unpaired electrons. The total spin of this atom will be

(A) 1

(B) 1.5

(C) 2

(D) 4

9. For a ‘ d ‘ electron , the orbital angular momentum is

(A) √6 h

(B) √2 h

(C) h

(D) 2 h

10. Which of the following pairs can form correct set of isosters ?

(A) MgS , CaF2

(B) C6H6 , B3N3H6

(C) CO , N2O

(D) All the above

ANSWER:

1. (D)   2. (A)  3. (D)   4. (B)  5. (A)   6. (D)  7. (A)   8. (C)  9. (A)   10. (B) 

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M.C.Q : Atomic Structure( 11 to 2 0 )

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