Atomic Structure — Set 5
Chemistry · परमाणु संरचना · Questions 41–50 of 50
Which principle states that electrons fill lower-energy orbitals first before moving to higher ones?
Correct Answer: D. Aufbau Principle
The Aufbau Principle provides the order in which electron shells are occupied. 'Aufbau' is a German word meaning 'building up'. This ensures the atom remains in its most stable ground state.
What is the atomic number of Carbon?
Correct Answer: C. 6
Carbon is the sixth element in the periodic table, meaning it has 6 protons. Its most common isotope has a mass number of 12. Carbon's unique ability to form four bonds makes it essential for life.
Which particle is identical to a Helium nucleus?
Correct Answer: A. Alpha particle
Alpha particles are composed of two protons and two neutrons. This is exactly the structure of a Helium-4 nucleus. They are heavy and slow compared to other types of nuclear radiation.
Who is considered the 'Father of Nuclear Physics'?
Correct Answer: A. Ernest Rutherford
Ernest Rutherford performed groundbreaking work on radioactivity and atomic structure. He discovered the concept of the radioactive half-life and the atomic nucleus. His work transformed our understanding of the subatomic world.
What is the total number of electrons in a Magnesium ion ($Mg^{2+}$) if its atomic number is 12?
Correct Answer: A. 10
A neutral Magnesium atom has 12 electrons to match its 12 protons. The '$2+$' charge indicates it has lost two electrons. Therefore, the ion has $12 - 2 = 10$ electrons.
Which of the following elements has zero neutrons in its nucleus?
Correct Answer: D. Hydrogen (Protium)
Protium is the only naturally occurring stable atom without a neutron. It consists of a single proton orbited by a single electron. This simplicity makes it a primary subject for early atomic studies.
What is the charge of a neutron?
Correct Answer: D. 0
Neutrons are electrically neutral particles found in the nucleus. They provide stability to the nucleus by mitigating proton repulsion. Because they have no charge, they can easily penetrate atomic nuclei.
The name 'atom' is derived from a Greek word meaning?
Correct Answer: B. Indivisible
The correct answer is 'Indivisible'. The term 'atomos' was used by ancient Greeks to describe a particle that cannot be cut. Philosophers like Democritus believed everything was made of these fundamental units. Modern science has since discovered that atoms are actually divisible into subatomic particles.
How many electrons are present in the outermost shell of Noble Gases (except Helium)?
Correct Answer: A. 8
Noble gases have a full valence shell containing 8 electrons. This configuration is exceptionally stable, making these elements chemically inert. This is known as the 'Octet' configuration.
Which subatomic particle was the last to be discovered among the following?
Correct Answer: A. Neutron
The neutron was not discovered until 1932 by James Chadwick. Its lack of charge made it much harder to detect than charged protons or electrons. Its discovery was essential for explaining the mass of atoms.