Question:
Which of the following pairs is an isobar?
Which of the following pairs is an isobar?
Show Hint
Isobars are elements with the same mass number but different atomic numbers.
Updated On: Jan 22, 2026
- \( ^1H \) and \( ^2H \)
- \( ^2H \) and \( ^3H \)
- \( ^{13}C \) and \( ^{12}C \)
- \( ^{18}Ar \) and \( ^{40}K \)
Hide Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Understanding the concept.
Isobars are atoms of different elements that have the same mass number. The mass number is the sum of protons and neutrons.
Step 2: Analyzing the options.
(1) \( ^1H \) and \( ^2H \): This is incorrect. These are isotopes of hydrogen, not isobars, because they have different mass numbers.
(2) \( ^2H \) and \( ^3H \): This is incorrect. These are isotopes of hydrogen, with different mass numbers.
(3) \( ^{13}C \) and \( ^{12}C \): Correct. These are isotopes of carbon, but they are not isobars since they have different numbers of neutrons but the same mass number (13 and 12).
(4) \( ^{18}Ar \) and \( ^{40}K \): This is incorrect. These are not isobars as they have different mass numbers.
Step 3: Conclusion.
The correct answer is (3) \( ^{13}C \) and \( ^{12}C \), which are isobars as they share the same mass number.
Isobars are atoms of different elements that have the same mass number. The mass number is the sum of protons and neutrons.
Step 2: Analyzing the options.
(1) \( ^1H \) and \( ^2H \): This is incorrect. These are isotopes of hydrogen, not isobars, because they have different mass numbers.
(2) \( ^2H \) and \( ^3H \): This is incorrect. These are isotopes of hydrogen, with different mass numbers.
(3) \( ^{13}C \) and \( ^{12}C \): Correct. These are isotopes of carbon, but they are not isobars since they have different numbers of neutrons but the same mass number (13 and 12).
(4) \( ^{18}Ar \) and \( ^{40}K \): This is incorrect. These are not isobars as they have different mass numbers.
Step 3: Conclusion.
The correct answer is (3) \( ^{13}C \) and \( ^{12}C \), which are isobars as they share the same mass number.
Was this answer helpful?
0
0
Top Questions on Isotopes
- The number of neutrons present in the more abundant isotope of boron is 'x'. Amorphous boron upon heating with air forms a product, in which the oxidation state of boron is 'y'. The value of x + y is ...
- Among the following, the correct statement is
- Which of the following atom has no isotope ?
- Which of the following statement is correct fro isotope of carbon?
- Most common isotopes of hydrogen (non-radioactive) is
View More Questions
Questions Asked in PSEB exam
- Derive an expression for the capacitance of a parallel plate capacitor with a dielectric slab between the plates.
- PSEB XII - 2025
- Electric and Magnetic Fields
- Read the following paragraph and answer the questions given below.
Ferromagnetic substances are those which get strongly magnetized when placed in an external magnetic field. They have strong tendency to move from a region of weak magnetic field to strong magnetic field, that is, they get strongly attracted to a magnet. The individual atoms (or ions or molecules) in a ferromagnetic material possess a dipole moment as in a paramagnetic material. However, they interact with one another in such a way that these spontaneously align themselves in a common direction over a macroscopic volume called domain. Each domain has a net magnetization. Typical domain size is 1 mm and the domain contains about \(10^{11}\) atoms. In the first instant the magnetization varies randomly from domain to domain and there is no bulk magnetization. When we apply an external magnetic field \(B_0\) the domains orient themselves in the direction of \(B_0\) and simultaneously that domain oriented in the direction of \(B_0\) grows in size. We may wonder as to what happens when the external field is removed, in some ferromagnetic materials the magnetization persists. Such materials are called hard magnetic materials of hard magnets. Alnico, an alloy of iron, aluminium, nickel, cobalt and copper is one such material. There is a class of magnetic materials in which the magnetization disappears on removal of the external field. Soft iron is one such material. Such materials are called soft ferromagnetic materials. There are number of elements which are ferromagnetic. Iron, cobalt, Nickel, gadolinium etc. The ferromagnetic property depends on temperature. At high enough temperature a ferromagnet becomes a paramagnet. That domain structure disintegrates with temperature. This disappearance of magnetization with the temperature is gradual.- PSEB XII - 2025
- Magnetic Field
- Write the assumptions, sign conventions and then derive the mirror formula for concave mirror.
- PSEB XII - 2025
- Mirrors And Reflections
- Using Gauss' theorem, derive an expression for electric field intensity due to a uniformly charged hollow sphere (shell) at a point outside the shell and at a point inside the shell.
- PSEB XII - 2025
- Electric and Magnetic Fields
- What is diffraction of light? Explain diffraction at a single slit and deduce the expression for the width of its central maxima.
View More Questions