Chemistry ยท Physics

Atomic Structure and Mass

308 Questions

Atomic structure and mass focus on the composition of atoms, including protons, neutrons, electrons, and isotopes. This topic is essential for the chemistry sections in engineering and civil services competitive exams. Review these questions to practice calculating atomic mass, neutron count, and isotopic distributions.

Atomic mass unit calculationsNeutron and proton countsIsotopic distribution averagesLaw of triadsRest energy of atoms

Atomic Structure and Mass Questions

Multiple choice

What is the mass number of an element?

  1. Number of protons in the nucleus

  2. Number of neutrons in the nucleus

  3. Number of electrons in the nucleus

  4. Number of electrons in the outermost shell
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

The mass number of an element is equal to the sum of the number of protons and neutrons in the nucleus of its atoms.

Multiple choice

What is an isotope?

  1. Atoms of the same element with different atomic numbers

  2. Atoms of the same element with different mass numbers

  3. Atoms of different elements with the same atomic number

  4. Atoms of different elements with the same mass number
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Isotopes are atoms of the same element that have the same atomic number but different mass numbers.

Multiple choice

Which element has the highest atomic mass?

  1. Uranium

  2. Plutonium

  3. Thorium

  4. Neptunium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Uranium has the highest atomic mass among naturally occurring elements, with an atomic mass of 238.02891.

Multiple choice

What is the term used to describe an atom with the same mass number but a different atomic number?

  1. (A) Isotope

  2. (B) Isomer

  3. (C) Ion

  4. (D) Molecule
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An isomer is an atom with the same mass number but a different atomic number.

Multiple choice

What is the defining characteristic of a neutral atom?

  1. Equal number of protons and electrons

  2. Equal number of neutrons and electrons

  3. Equal number of protons and neutrons

  4. Equal number of electrons and neutrons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A neutral atom possesses an equal number of protons and electrons, resulting in a balanced electrical charge, with the positive charge of the protons canceling out the negative charge of the electrons.

Multiple choice

The law of multiple proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a simple ratio.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The law of multiple proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a simple ratio.

Multiple choice

What is the detection limit of Atomic Absorption Spectroscopy?

  1. 10-100 ppb.

  2. 1-10 ppb.

  3. 0.1-1 ppb.

  4. 0.01-0.1 ppb.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The detection limit of Atomic Absorption Spectroscopy is typically in the range of 0.01-0.1 ppb.

Multiple choice

What is the name of the smallest particle of an element that retains all of its chemical properties?

  1. Atom

  2. Molecule

  3. Ion

  4. Compound
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An atom is the smallest particle of an element that retains all of its chemical properties.