In 2H₂ + O₂ → 2H₂O, how many oxygen atoms appear on each side?
A) 1 B) 2 C) 3 D) 4 Answer: B Explanation: One oxygen molecule has two oxygen atoms on the […]
Atomic Structure, Chemistry
Atomic Structure
Atomic Structure, Chemistry
What does mass number A count?
A) Electrons plus photons B) Only valence electrons C) Protons plus neutrons in a nucleus D) Only protons Answer: C […]
Atomic Structure, Chemistry
What does the Aufbau principle predict?
A) All electrons occupy the same orbital B) Lower-energy orbitals fill before higher-energy orbitals ordinarily C) Neutrons determine pH D) […]
Atomic Structure, Chemistry
What does the principal quantum number n primarily indicate?
A) The number of neutrons B) The bond order C) The electron's principal energy level D) The solution concentration Answer: […]
Atomic Structure, Chemistry
What happens to total atomic mass in a closed-system chemical reaction?
A) It always doubles B) It remains conserved C) It disappears D) It becomes only light Answer: B Explanation: Atoms […]
Atomic Structure, Chemistry
What happens when an electron emits a photon in an atomic spectrum?
A) It gains a proton B) It falls to a lower energy state C) It becomes a neutron D) It […]
Atomic Structure, Chemistry
What is an excited electronic state?
A) An electron arrangement above the lowest-energy configuration B) An atom with no protons C) A solution at pH 7 […]
Atomic Structure, Chemistry
What is the electron configuration of a neutral sodium atom in noble-gas notation?
A) [Ne]3s² B) [Ar]3s¹ C) [Ne]3s¹ D) [Ne]3p¹ Answer: C Explanation: Sodium has eleven electrons, ten in a neon core. […]
Atomic Structure, Chemistry
What is the maximum electron capacity of a d subshell?
A) 2 electrons B) 6 electrons C) 10 electrons D) 14 electrons Answer: C Explanation: A d subshell contains five […]
Atomic Structure, Chemistry
What is the maximum electron capacity of an f subshell?
A) 6 electrons B) 14 electrons C) 10 electrons D) 18 electrons Answer: B Explanation: An f subshell consists of […]