Chemistry ยท Physics

Atomic Structure and Mass

277 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 density of the interstellar medium?

  1. 1 atom per cubic centimeter

  2. 10 atoms per cubic centimeter

  3. 100 atoms per cubic centimeter

  4. 1,000 atoms per cubic centimeter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The interstellar medium is the matter that exists between stars in a galaxy, and it has a density of about 1 atom per cubic centimeter.

Multiple choice

What is the GUT prediction for the ratio of the masses of the proton and the electron?

  1. 1/1836

  2. 1/1000

  3. 1/100

  4. 1/10
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

GUTs predict that the ratio of the masses of the proton and the electron is approximately 1/1836.

Multiple choice

What is the atomic 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
A Correct answer
Explanation

The atomic number of an element is equal to the number of protons in the nucleus of its atoms.

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

What is the average density of the Interstellar Medium?

  1. 1 atom per cubic centimeter

  2. 10 atoms per cubic centimeter

  3. 100 atoms per cubic centimeter

  4. 1,000 atoms per cubic centimeter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Interstellar Medium is extremely tenuous, with an average density of only about 1 atom per cubic centimeter.

Multiple choice

What is the approximate mass range of neutron stars?

  1. 1.4 - 2.1 solar masses

  2. 0.1 - 0.5 solar masses

  3. 10 - 20 solar masses

  4. 0.01 - 0.1 solar masses
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neutron stars typically have masses between 1.4 and 2.1 solar masses. This mass range is known as the Chandrasekhar limit, which represents the maximum mass a white dwarf can support before collapsing under its own gravity.

Multiple choice

What is the mass range of WIMPs?

  1. 10^-12 eV to 10^-6 eV

  2. 10^-6 eV to 10^-3 eV

  3. 10^-3 eV to 10^3 eV

  4. 10^3 eV to 10^12 eV
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

WIMPs are thought to have a mass range of 10^-3 eV to 10^3 eV.

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 typical density of a solar prominence?

  1. 10^8 particles/cm^3

  2. 10^9 particles/cm^3

  3. 10^10 particles/cm^3

  4. 10^11 particles/cm^3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The typical density of a solar prominence is around 10^9 particles/cm^3, which is significantly lower than the density of the surrounding corona.

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 approximate mass of the Local Group?

  1. 1 trillion solar masses

  2. 2 trillion solar masses

  3. 3 trillion solar masses

  4. 4 trillion solar masses
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Local Group is approximately 1 trillion solar masses.

Multiple choice

What is the typical mass range of neutron stars?

  1. 1.4 - 3 solar masses

  2. 0.1 - 1 solar masses

  3. 10 - 20 solar masses

  4. 0.01 - 0.1 solar masses
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neutron stars typically have masses ranging from 1.4 to 3 solar masses. This is known as the Chandrasekhar limit, which represents the maximum mass a white dwarf can support before collapsing into a neutron star.

Multiple choice

What is the approximate mass range of brown dwarfs?

  1. 0.01 - 0.08 solar masses

  2. 0.08 - 0.13 solar masses

  3. 0.13 - 0.25 solar masses

  4. 0.25 - 0.5 solar masses
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Brown dwarfs typically have masses ranging from 0.01 to 0.08 solar masses.

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.