Knowledge batch

#Chemistry😎😎

1. Which combination of quantum numbers is not allowed?
A. n=4, l=3, ml=-2, ms=+1/2
B. n=3, l=2, ml=3, ms=-1/2
C. n=2, l=1, ml=0, ms=+1/2
D. n=4, l=0, ml=0, ms=-1/2

2. According to Pauli’s exclusion principle, an orbital can contain:
A. One electron with any spin
B. Two electrons with the same spin
C. Two electrons with opposite spins
D. Any number of electrons

3. What is the maximum number of electrons in the level?
A. 16
B. 18
C. 32
D. 36

4. Which orbital is filled after 3p according to the Aufbau principle?
A. 3d
B. 4s
C. 4p
D. 3f

5. Hund’s rule states that:
A. Electrons fill orbitals singly before pairing
B. Orbitals fill in order of increasing energy
C. No two electrons can have same quantum numbers
D. Orbitals have the same energy

6. The element with configuration [Ne] 3s²3p³ is:
A. P
B. S
C. Si
D. Cl

7. Which statement about orbitals is true?
A. s-orbitals are dumbbell-shaped
B. p-orbitals have 3 orientations
C. d-orbitals have 2 orientations
D. f-orbitals are spherical

8. The first ionization energy of an element increases across a period because:
A. Atomic radius increases
B. Nuclear charge increases
C. Electron shielding increases
D. Number of shells increases

9. Which is a pair of isotopes?
A. ¹²C & ¹⁴N
B. ³⁵Cl & ³⁷Cl
C. ¹⁶O & ¹⁶S
D. ²³Na & ²⁴Mg

10. Which element has the highest electronegativity?
A. Na
B. O
C. Al
D. K

11. An orbital with and is:
A. 3s
B. 3p
C. 3d
D. 3f

12. Which of the following violates the Pauli exclusion principle?
A. Two electrons in the same orbital with opposite spins
B. Two electrons in the same orbital with same spins
C. One electron in 2p orbital
D. One electron in 1s orbital

13. Which of the following has a full outer shell?
A. Ne
B. Na
C. Cl
D. Mg

14. The number of valence electrons in S is:
A. 4
B. 5
C. 6
D. 7

15. Which of the following elements is a transition metal?
A. Sc
B. Ca
C. K
D. Cl

16. The shape of a p-orbital is:
A. Spherical
B. Dumbbell
C. Double dumbbell
D. Circular

17. Which of these atoms has the largest atomic radius?
A. Li
B. Be
C. B
D. C

18. Which element’s electron configuration ends with 4s¹ instead of 4s² due to stability?
A. Cr
B. Ca
C. K
D. Zn

19. Which element is in period 3 and group 15?
A. P
B. S
C. Si
D. Al

20. Which factor mainly determines the chemical behavior of an element?
A. Number of neutrons
B. Number of protons
C. Number of valence electrons
D. Atomic mass

Workout
1. An atom has the electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁴.
(a) Identify the element.
(b) Determine its group and period.
(c) How many valence electrons does it have?

2. For an electron in the 3d orbital:
(a) Write possible values of .
(b) What is the total number of electrons possible in the 3d subshell?
(c) Draw an orbital diagram for 3d⁵.

3. Consider an element with atomic number 17:
(a) Write its full electron configuration.
(b) Write the shorthand (noble gas) electron configuration.
(c) Determine its number of valence electrons and predict its common ion.

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