{"id":88194,"date":"2025-06-01T07:04:22","date_gmt":"2025-06-01T07:04:22","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=88194"},"modified":"2025-06-01T07:04:22","modified_gmt":"2025-06-01T07:04:22","slug":"which-one-of-the-following-statements-is-correct-26","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-is-correct-26\/","title":{"rendered":"Which one of the following statements is correct?"},"content":{"rendered":"

Which one of the following statements is correct?<\/p>\n

[amp_mcq option1=”Rutherford\u2019s alpha-particle scattering experiment led to the discovery of electron.” option2=”J J Thomson suggested that the nucleus of an atom contains protons.” option3=”The atomic number of an element is the same as the number of protons in the nucleus of its atom.” option4=”The mass number of an atom is equal to the number of electrons in its shells.” correct=”option3″]<\/p>\n

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\n
This question was previously asked in<\/div>\n
UPSC NDA-2 – 2015<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nLet’s analyze each statement:
\nA) Rutherford\u2019s alpha-particle scattering experiment led to the discovery of the atomic *nucleus*, not the electron. The electron was discovered by J.J. Thomson through his cathode ray experiments.
\nB) J J Thomson proposed the ‘plum pudding’ model, where electrons were embedded in a diffuse positive charge. Rutherford, based on his experiment, proposed the nuclear model with a central positive nucleus containing protons and neutrons (neutrons were discovered later by Chadwick).
\nC) The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This statement is correct.
\nD) The mass number (A) of an atom is the total number of protons and neutrons in the nucleus (A = Z + N). It is not equal to the number of electrons in its shells (unless the atom is neutral, but even then, mass number is protons + neutrons, not just electrons).
\n<\/section>\n
\nThe atomic number of an element is a fundamental property that uniquely identifies it and is equal to the number of protons in the nucleus.
\n<\/section>\n
\nRutherford’s experiment provided evidence for a small, dense, positively charged nucleus. J.J. Thomson’s model was disproven by Rutherford’s findings. The number of electrons in a neutral atom is equal to the number of protons (the atomic number), but this is not the definition of mass number. The mass number is the sum of protons and neutrons, which account for most of the atom’s mass.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

Which one of the following statements is correct? [amp_mcq option1=”Rutherford\u2019s alpha-particle scattering experiment led to the discovery of electron.” option2=”J J Thomson suggested that the nucleus of an atom contains protons.” option3=”The atomic number of an element is the same as the number of protons in the nucleus of its atom.” option4=”The mass number of … <\/p>\n

Detailed SolutionWhich one of the following statements is correct?<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1094],"tags":[1443,1203,1128],"class_list":["post-88194","post","type-post","status-publish","format-standard","hentry","category-upsc-nda-2","tag-1443","tag-nuclear-physics","tag-physics","no-featured-image-padding"],"yoast_head":"\nWhich one of the following statements is correct?<\/title>\n<meta name=\"description\" content=\"Let's analyze each statement: A) Rutherford\u2019s alpha-particle scattering experiment led to the discovery of the atomic *nucleus*, not the electron. The electron was discovered by J.J. Thomson through his cathode ray experiments. B) J J Thomson proposed the 'plum pudding' model, where electrons were embedded in a diffuse positive charge. Rutherford, based on his experiment, proposed the nuclear model with a central positive nucleus containing protons and neutrons (neutrons were discovered later by Chadwick). C) The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This statement is correct. D) The mass number (A) of an atom is the total number of protons and neutrons in the nucleus (A = Z + N). It is not equal to the number of electrons in its shells (unless the atom is neutral, but even then, mass number is protons + neutrons, not just electrons). The atomic number of an element is a fundamental property that uniquely identifies it and is equal to the number of protons in the nucleus.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-is-correct-26\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Which one of the following statements is correct?\" \/>\n<meta property=\"og:description\" content=\"Let's analyze each statement: A) Rutherford\u2019s alpha-particle scattering experiment led to the discovery of the atomic *nucleus*, not the electron. The electron was discovered by J.J. Thomson through his cathode ray experiments. B) J J Thomson proposed the 'plum pudding' model, where electrons were embedded in a diffuse positive charge. Rutherford, based on his experiment, proposed the nuclear model with a central positive nucleus containing protons and neutrons (neutrons were discovered later by Chadwick). C) The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This statement is correct. D) The mass number (A) of an atom is the total number of protons and neutrons in the nucleus (A = Z + N). It is not equal to the number of electrons in its shells (unless the atom is neutral, but even then, mass number is protons + neutrons, not just electrons). 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The electron was discovered by J.J. Thomson through his cathode ray experiments. B) J J Thomson proposed the 'plum pudding' model, where electrons were embedded in a diffuse positive charge. Rutherford, based on his experiment, proposed the nuclear model with a central positive nucleus containing protons and neutrons (neutrons were discovered later by Chadwick). C) The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This statement is correct. D) The mass number (A) of an atom is the total number of protons and neutrons in the nucleus (A = Z + N). It is not equal to the number of electrons in its shells (unless the atom is neutral, but even then, mass number is protons + neutrons, not just electrons). The atomic number of an element is a fundamental property that uniquely identifies it and is equal to the number of protons in the nucleus.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-is-correct-26\/","og_locale":"en_US","og_type":"article","og_title":"Which one of the following statements is correct?","og_description":"Let's analyze each statement: A) Rutherford\u2019s alpha-particle scattering experiment led to the discovery of the atomic *nucleus*, not the electron. The electron was discovered by J.J. Thomson through his cathode ray experiments. B) J J Thomson proposed the 'plum pudding' model, where electrons were embedded in a diffuse positive charge. Rutherford, based on his experiment, proposed the nuclear model with a central positive nucleus containing protons and neutrons (neutrons were discovered later by Chadwick). C) The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This statement is correct. D) The mass number (A) of an atom is the total number of protons and neutrons in the nucleus (A = Z + N). It is not equal to the number of electrons in its shells (unless the atom is neutral, but even then, mass number is protons + neutrons, not just electrons). The atomic number of an element is a fundamental property that uniquely identifies it and is equal to the number of protons in the nucleus.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-is-correct-26\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T07:04:22+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-is-correct-26\/","url":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-is-correct-26\/","name":"Which one of the following statements is correct?","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T07:04:22+00:00","dateModified":"2025-06-01T07:04:22+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"Let's analyze each statement: A) Rutherford\u2019s alpha-particle scattering experiment led to the discovery of the atomic *nucleus*, not the electron. 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