Isotopes and Isobars

Chemistry ⇒ Atomic Structure and the Periodic Table

Isotopes and Isobars starts at 8 and continues till grade 12. QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Isotopes and Isobars. How you perform is determined by your score and the time you take. When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.

See sample questions for grade 10

A sample contains 75% ³⁵Cl and 25% ³⁷Cl. Calculate the average atomic mass of chlorine.

Calculate the number of neutrons in ³⁷Cl (atomic number 17).

Calculate the number of neutrons in ⁴⁰K (atomic number 19).

Define isotopes.

Describe one difference between isotopes and isobars.

Describe one use of isotopes in scientific research.

Explain why isobars have different chemical properties.

Explain why isotopes of the same element have different mass numbers.

Explain why isotopes of the same element have similar chemical properties.

Explain why the average atomic mass of an element is usually not a whole number.

Give an example of a pair of isobars.

If an atom has 17 protons and 20 neutrons, what is its mass number?

If an atom has 20 protons and 20 neutrons, what is its mass number?

State one use of radioactive isotopes in medicine.

The atomic number of potassium is 19. How many electrons are present in a neutral atom of potassium-40?

The atomic number of sodium is 11. How many protons are present in all isotopes of sodium?

Which property is used to distinguish between isotopes of an element?

A scientist discovers two atoms: Atom X has 15 protons and 16 neutrons, Atom Y has 16 protons and 15 neutrons. Are these atoms isotopes, isobars, or neither? Justify your answer.

An element X has two naturally occurring isotopes: ²⁹X (abundance 60%) and ³⁰X (abundance 40%). Calculate the average atomic mass of element X.

Explain, with reference to their subatomic particles, why ⁴⁰Ca and ⁴⁰Ar are considered isobars but not isotopes.