Structure of Atom MCQ Quiz - Objective Question with Answer for Structure of Atom - Download Free PDF

The correct answer is Phosphorous.

Key Points

• The present number of atoms in any molecule of an element is called its atomicity.
• Tetra atomic elements are those which are made up of four atoms. 
• Phosphorous exists as molecules made up of four atoms in a tetrahedral structure.
• Each phosphorus molecule consists of four atoms of phosphorus.

Important Points

• The following table shows the atomicity of some elements. 

The correct answer is 256 u.

Key Points

• The atomic mass of sulphur is 32 u.
• Sulphur exists as S₈ molecules.
• To find the molecular mass of sulphur, multiply the atomic mass of sulphur by the number of atoms in one molecule of sulphur.
• Calculation: 32u×8=256u" id="MathJax-Element-1-Frame" role="presentation" style="position: relative;" tabindex="0">32u×8=256u32u×8=256u $32 \, \text{u} \times 8 = 256 \, \text{u}$
• Thus, the molecular mass of sulphur is 256 u.

 Additional Information

• Atomic Mass Unit (u)
  • An atomic mass unit (u) is a standard unit of mass that quantifies mass on an atomic or molecular scale.
  • It is defined as one-twelfth of the mass of an unbound atom of carbon-12 at rest and in its ground state.
• Molecular Mass
  • The molecular mass (or molecular weight) is the mass of a given molecule and is calculated as the sum of the atomic masses of the atoms in the molecule.
  • It is typically measured in atomic mass units (u).

The correct answer is Hydrogen.

Key Points

• Neutrons are present in the nucleus of all atoms, except hydrogen.
• Hydrogen is the lightest element. 
• It exists as the stable isotope Deuterium and the unstable, radioactive isotope Tritium.
• Hydrogen (H) is a colourless, odourless, tasteless, flammable gas.
• It is the simplest chemical element.
• The hydrogen has a nucleus consisting of a proton bearing one unit of positive electrical charge, and an electron, bearing one unit of negative electrical charge, is also associated with this nucleus, but no neutron.
• It exists as a diatomic molecule, H₂.

The correct answer is Electron.

Key Points

• Electrons are subatomic particles with a negative electrical charge of -1 elementary charge (approximately -1.602 × 10^-19 coulombs).
• Electrons are found outside the nucleus of an atom in regions called electron clouds or orbitals.
• They are much lighter than protons and neutrons, with a mass of approximately 9.109 × 10^-31 kilograms, which is about 1/1836 of a proton's mass.
• The movement of electrons in conductive materials is the basis of electricity.
• Electrons play a critical role in chemical bonding, determining the way atoms interact and form molecules.

Additional Information

• Proton
  • Protons are positively charged subatomic particles found in the nucleus of an atom.
  • Each proton carries a charge of +1 elementary charge (1.602 × 10^-19 coulombs).
  • Protons define the atomic number of an element, which determines its identity.
• Neutron
  • Neutrons are neutral subatomic particles found in the nucleus of an atom.
  • They have no electrical charge and a mass slightly greater than that of a proton.
  • Neutrons play a key role in stabilizing the nucleus by offsetting the repulsion between positively charged protons.
• Positron
  • Positrons are the antimatter counterparts of electrons, with the same mass but a positive charge.
  • They are produced in processes like beta-plus decay and annihilate when they come into contact with electrons, releasing energy in the form of gamma rays.
• Subatomic Particles
  • An atom consists of three main types of subatomic particles: protons, neutrons, and electrons.
  • Protons and neutrons are found in the atomic nucleus, while electrons orbit the nucleus.
  • The interactions between these particles dictate the atom's physical and chemical properties.

The correct answer is spiral.

Key Points

• The Rutherford nuclear model predicts that electrons revolve around the nucleus in orbits due to electrostatic forces.
• According to classical electromagnetic theory, an accelerating electron would emit radiation, losing energy in the process.
• This energy loss would cause the electron to spiral inwards towards the nucleus.
• As the electron spirals inwards, it would eventually collide with the nucleus, leading to the instability of the atom.
• This instability, predicted by the Rutherford model, contradicts the observed stability of atoms.

Additional Information

• Rutherford's Nuclear Model
  • Proposed by Ernest Rutherford in 1911 based on the gold foil experiment.
  • Suggested that most of the atom's mass is concentrated in a small, positively charged nucleus.
  • Electrons revolve around this nucleus similar to planets orbiting the sun.
• Classical Electromagnetic Theory
  • States that any charged particle undergoing acceleration emits electromagnetic radiation.
  • This emission of radiation causes the particle to lose energy.
• Niels Bohr's Model
  • Proposed in 1913 to address the limitations of Rutherford's model.
  • Introduced the concept of quantized electron orbits where electrons do not radiate energy while in these stable orbits.
• Quantum Mechanics
  • Further developed the understanding of atomic structure and electron behavior.
  • Explains the stability of atoms through principles such as wave-particle duality and the uncertainty principle.

• The word ‘atom’ is coined by Democritus.
• He suggested that if we go on dividing matter at a certain point the atom becomes indivisible or cannot be divided further.
• He called these particles as atoms (Indivisible).

• Group 1 elements in the Periodic table are known as Alkali metals
• They have ns1 outermost configuration and belong to the S-block Elements.
• They also have a strong tendency to donate their valence electrons in the outermost shell to form strong ionic bonds.
• It contains elements from Lithium (Li) to Francium (Fr).

The correct answer is Phosphorous.

Key Points

• The present number of atoms in any molecule of an element is called its atomicity.
• Tetra atomic elements are those which are made up of four atoms. 
• Phosphorous exists as molecules made up of four atoms in a tetrahedral structure.
• Each phosphorus molecule consists of four atoms of phosphorus.

Important Points

• The following table shows the atomicity of some elements. 

• Electron Shell (also called a Principle energy level) is the region where electrons revolve around the nucleus of an atom.
• The general formula of filling electron in the shell is 2(n²); where n is the number of the shell.

Key Points

• J. Chadwick discovered the presence of neutrons in the nucleus of an atom.
• An atom is the smallest unit of any chemical element.
• Atom is made up of electrons, protons, and neutrons.
• The electron carries a negative charge, proton carries an equal to an electron but a positive charge and a neutron is neutral.
• Proton and neutrons reside in the nucleus while the electron revolves around the nucleus.

Hence, we can conclude that J. Chadwick discovered neutrons.

Additional Information

The correct answer is option 1, i.e. Fluorine.

• Fluorine is the most electronegative element.
• As we move right in a period, the electronegativity keeps increasing up to the halogens.
• This is because the number of electrons keeps increasing in the same valence shell so hold of the nucleus on the electrons is tight.
• And as we move down in a group, the electronegativity decreases. This is due to the fact that the number of shells keeps increasing down the group so the hold of the nucleus on the valence electron(s) keeps decreasing.
• Since Flourine is the first member of the halogen family (the rightmost group before noble gases), therefore it is the most electronegative element.

• Newlands Law of Octaves classification attempted to arrange elements by the atomic weight
• According to Newlands Law of Octaves classification, the eighth element starting from the given one kind is a repetition of the first element in the given kind
• This is similar to the property of musical notes
•  The eighth element would have similar atomic weight as that of the first one
• In this way, Thorium was the last element in the Newlands Law of Octaves classification

• Atomic number 56, Barium belongs to s - block elements.
• Electronic configuration for the Barium [Xe]6s²
• Modern Periodic Table is classified into the following elements - p-block, s-block, d-block, and f-block.
• s-block elements include alkali metals and alkaline earth metals.

The correct answer is helium.

Key Points

• Alpha Particle
  • α-particles consist of two protons and two neutrons.
  • They are doubly-charged helium ions. Since they have a mass of 4 u, the fast-moving α-particles have considerable energy.
  •  An alpha particle is obtained by removing 2 electrons from a helium atom. So, an alpha particle is a doubly-charged helium ion.
•  Helium:
  • Helium is a chemical element with the symbol He and atomic number 2.
  • It is a colourless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.
  •  Its boiling and melting point are the lowest among all the elements.
  • It is the second lightest and most abundant element in the observable universe (hydrogen is the lightest and most abundant).

Additional Information

• Lithium
  • ​Lithium is a chemical element with the symbol Li and atomic number 3.
  • It is a soft, silver-white metal belonging to the alkali metal group of chemical elements.
• ​Beryllium
  • Beryllium is very similar to Aluminium.
  • Beryllium is soft and has a low density.
  • It is used in gears and in alloys with copper or nickel.
  • Beryllium is used in Nuclear Reactors.
  • Oxides of Beryllium have a high melting point.
• Hydrogen​
  • Hydrogen was discovered by Henry Cavendish.
  • Hydrogen gas is called as the fuel of the future.
  • Most abundant element in the universe: Hydrogen.
  • Most abundant element on earth's crust: Oxygen
  • Hydrogen is the 'lightest element' in the periodic table.
  • Lithium is the 'lightest metal' in the periodic table.

The correct answer is option 3, i.e. John Dalton.