Which of the following sets of quantum numbers is impossible? MCQ with Answer and Explanation

Which of the following sets of quantum numbers is impossible?
A. n=2, l=1, m=-1, s=-1/2
B. n=1, l=0, m=0, s=+1/2
C. n=4, l=3, m=0, s=-1/2
D. n=3, l=2, m=-3, s=+1/2
Answer: Option D
Solution (By JKSSB Mock Tests)
The magnetic quantum number (m) can only take integer values ranging from -l to +l. For n=3, l can be 2 (a d-orbital). If l=2, the possible values for m are -2, -1, 0, +1, +2. The value m=-3 is outside this range, making this set of quantum numbers impossible.

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Practice More chemistry Questions

Question #1
Which of the following is an example of a negative catalyst?
A. Alcohol in chloroform storage to prevent phosgene formation
B. MnO₂ in H₂O₂ decomposition
C. Pt in SO₂ oxidation
D. Fe in Haber process

Correct Answer: Option A


Explanation:
A small amount of ethanol (alcohol) is added to chloroform to inhibit its oxidation by air to toxic phosgene (COCl₂) and HCl. Ethanol acts as a negative catalyst (stabilizer) by consuming any formed phosgene. MnO₂, Pt, Fe are positive catalysts. Negative catalysts are also called inhibitors, used to prevent undesirable reactions.

This question belongs to: Science chemistry
Question #2
A solution has [H⁺] = 10⁻⁴ M. Its pH is:
A. 1
B. 7
C. 10
D. 4

Correct Answer: Option D


Explanation:
pH = -log[H⁺] = -log(10⁻⁴) = 4. The solution is acidic. pOH = 14 - pH = 10, so [OH⁻] = 10⁻¹⁰ M. pH scale ranges 0-14 (typically). pH < 7 acidic, pH = 7 neutral, pH > 7 basic. Pure water has [H⁺] = 10⁻⁷ M, pH=7.

This question belongs to: Science chemistry
Question #3
Which indicator is red in acidic medium and yellow in basic medium?
A. Turmeric
B. Phenolphthalein
C. Litmus
D. Methyl orange

Correct Answer: Option D


Explanation:
Methyl orange is red at pH < 3.1 and yellow at pH > 4.4. Litmus: red in acid, blue in base. Phenolphthalein: colorless in acid, pink in base. Turmeric: yellow in acid, reddish-brown in base.

This question belongs to: Science chemistry