Atoms MCQs with Answers

Which of the following samples contains the most atoms?

• A.1.0 mole of water (H₂O)
• B.2.0 moles of hydrogen chloride (HCl)
• C.1.5 moles of carbon dioxide (CO₂)
• D.1.0 mole of ammonia (NH₃)

Which of the following has the smallest atomic radius?

• A.Cl
• B.P
• C.S
• D.Si

Past Paper MCQ

Isotopes of an element have the same number of _?

• A.Neutrons
• B.Protons
• C.Electrons
• D.Nucleons

If maximum value of principal quantum number for an atom is four, then total number of electrons in an atom will be?

• A.18
• B.32
• C.36
• D.60

The first excitation energy of H atom will be ?

• A.1.51 eV
• B.13.6 eV
• C.3.4 eV
• D.10.2 eV

What are the extremely tiny particles that make up atoms called?

• A.Protons, neutrons, and electrons
• B.Molecules, ions, and isotopes
• C.Quarks, leptons, and bosons
• D.Cells, tissues, and organs

Whether the cathode ray particles have positive or negative charge can be determined by ?

• A.Measuring their speed in a discharge tube
• B.Heating them in a vacuum tube
• C.Passing them through a magnetic field only
• D.Passing them through oppositely charged plates

Atom is made up of smallest particles called?

• A.Molecules
• B.Subatomic particles
• C.Compounds
• D.Ions

All sets of four quantum numbers in an atom can be explained by which principle?

• A.Aufbau principle
• B.Hund's rule
• C.Pauli exclusion principle
• D.Heisenberg uncertainty principle

One-gram atom of chlorine is equal to?

• A.One gram of chlorine
• B.35.5 grams of chlorine
• C.Both a and b
• D.None of these