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An atom 70 X has 31 electrons. How many neutrons are there in its nucleus?
For a neutral atom of element X, the number of protons equals the number of electrons, which is 31. The superscript 70 represents the mass number, which is the total count of protons and neutrons combined. Subtracting 31 protons from the mass number 70 yields 39 neutrons. Therefore, there are 39 neuRead more
For a neutral atom of element X, the number of protons equals the number of electrons, which is 31. The superscript 70 represents the mass number, which is the total count of protons and neutrons combined. Subtracting 31 protons from the mass number 70 yields 39 neutrons. Therefore, there are 39 neutrons in its nucleus.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/
See lessBoth Rutherford’s and Bohr’s models have electrons orbiting the nucleus. Why did Rutherford’s model fail to explain atomic stability, while Bohr’s model succeeded?
According to classical physics, an electron in Rutherford's model accelerates along a curved path and must continuously radiate energy, spiraling inward until it crashes into the nucleus. Bohr succeeded because he proposed that electrons revolve exclusively within discrete, fixed orbits termed statiRead more
According to classical physics, an electron in Rutherford’s model accelerates along a curved path and must continuously radiate energy, spiraling inward until it crashes into the nucleus. Bohr succeeded because he proposed that electrons revolve exclusively within discrete, fixed orbits termed stationary states or energy levels. Moving within these specific allowed shells, an electron does not emit radiation, ensuring complete atomic stability.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/
See lessFind the following information for the elements shown in Fig. 8.17: (i) Name of the element (ii) Symbol (iii) Total number of electrons (iv) Number of valence electrons (v) Valency of the element (vi) Number of protons (vii) Atomic number
For element a: Lithium, symbol Li, total electrons 3, valence electrons 1, valency 1, protons 3, atomic number 3. For element b: Carbon, symbol C, total electrons 6, valence electrons 4, valency 4, protons 6, atomic number 6. For element c: Phosphorus, symbol P, total electrons 15, valence electronsRead more
For element a: Lithium, symbol Li, total electrons 3, valence electrons 1, valency 1, protons 3, atomic number 3. For element b: Carbon, symbol C, total electrons 6, valence electrons 4, valency 4, protons 6, atomic number 6. For element c: Phosphorus, symbol P, total electrons 15, valence electrons 5, valency 3, protons 15, atomic number 15. For element d: Fluorine, symbol F, total electrons 9, valence electrons 7, valency 1, protons 9, atomic number 9.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/
See lessMagnesium is essential for many biological processes, including muscle contraction. For an atom of magnesium with a mass number of 24 and atomic number 12, determine the number of (i) protons, (ii) neutrons, (iii) electrons and also illustrate the arrangement of electrons in a magnesium atom.
For magnesium, the atomic number of 12 establishes 12 protons and 12 electrons in a neutral atom. Subtracting the atomic number from the mass number 24 yields 12 neutrons. Applying the Bohr-Bury rules, the arrangement of its twelve electrons across energy shells is K-shell contains 2 electrons, L-shRead more
For magnesium, the atomic number of 12 establishes 12 protons and 12 electrons in a neutral atom. Subtracting the atomic number from the mass number 24 yields 12 neutrons. Applying the Bohr-Bury rules, the arrangement of its twelve electrons across energy shells is K-shell contains 2 electrons, L-shell contains 8 electrons and M-shell contains 2 electrons, written as 2, 8, 2.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/
See lessAssertion (A): The discovery of subatomic particles helped in understanding the atomic structure. Reason (R): The number of electrons is equal to the number of protons in an atom. Choose the correct option: (i) Both A and R are true and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true.
Option (ii) is the correct choice. Assertion A is true because discovering electrons, protons and neutrons explained internal organization, chemical behavior and bonding. Reason R is also true because an atom contains equal counts of protons and electrons, ensuring neutrality. However, statement R sRead more
Option (ii) is the correct choice. Assertion A is true because discovering electrons, protons and neutrons explained internal organization, chemical behavior and bonding. Reason R is also true because an atom contains equal counts of protons and electrons, ensuring neutrality. However, statement R simply describes atomic electrical balance and does not serve as the complete scientific explanation for how subatomic discoveries unveiled overall atomic structure.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/
See less