{"id":205724,"date":"2025-03-25T10:54:37","date_gmt":"2025-03-25T10:54:37","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=205724"},"modified":"2025-03-25T10:54:39","modified_gmt":"2025-03-25T10:54:39","slug":"an-isotope-of-which-element-is-used-as-the-standard-for-the-relative-mass-scale-for-atoms-2","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/03\/25\/an-isotope-of-which-element-is-used-as-the-standard-for-the-relative-mass-scale-for-atoms-2\/","title":{"rendered":"An isotope of which element is used as the standard for the relative mass scale for atoms"},"content":{"rendered":"\n<p>An isotope of which element is used as the standard for the relative mass scale for atoms?<\/p>\n\n\n\n<p>A) carbon<\/p>\n\n\n\n<p>B) oxygen<\/p>\n\n\n\n<p>C) hydrogen<\/p>\n\n\n\n<p>D) helium<\/p>\n\n\n\n<p><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-6-color\"><strong>The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Correct Answer:<\/h3>\n\n\n\n<p><strong>A) Carbon<\/strong><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Explanation:<\/h3>\n\n\n\n<p>The isotope used as the standard for the relative mass scale of atoms is <strong>carbon-12 (\u00b9\u00b2C)<\/strong>. The atomic mass unit (amu), also known as the <strong>Dalton (Da)<\/strong>, is defined based on this isotope.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Why Carbon-12?<\/strong><\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Definition of Atomic Mass Unit<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>One atomic mass unit (1 amu) is defined as <strong>1\/12th the mass of a single carbon-12 atom<\/strong>. This means that the mass of a carbon-12 atom is exactly <strong>12 amu<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Historical Development<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Initially, hydrogen (the lightest element) and oxygen were considered as reference standards.<\/li>\n\n\n\n<li>In the early 20th century, oxygen-16 (\u00b9\u2076O) was widely used, but differences in measurement scales between physicists and chemists led to inconsistencies.<\/li>\n\n\n\n<li>In 1961, the International Union of Pure and Applied Chemistry (IUPAC) officially adopted <strong>carbon-12<\/strong> as the standard due to its stable and abundant nature.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Advantages of Carbon-12 as a Standard<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Stability<\/strong>: Carbon-12 is a stable isotope, meaning it does not undergo radioactive decay.<\/li>\n\n\n\n<li><strong>Abundance<\/strong>: It is the most common isotope of carbon, making up about <strong>98.9%<\/strong> of natural carbon.<\/li>\n\n\n\n<li><strong>Precise Measurement<\/strong>: Its mass can be accurately measured using mass spectrometry, ensuring consistency in atomic mass calculations.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Use in Chemistry and Physics<\/strong><\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Carbon-12 serves as the <strong>basis for determining the atomic masses of all other elements<\/strong>.<\/li>\n\n\n\n<li>It is essential in <strong>molecular weight calculations, stoichiometry, and isotope studies<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p>Thus, <strong>carbon-12 is the internationally accepted reference isotope for atomic mass measurements<\/strong>.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/03\/image-1395.png\" alt=\"\" class=\"wp-image-205725\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>An isotope of which element is used as the standard for the relative mass scale for atoms? A) carbon B) oxygen C) hydrogen D) helium The correct answer and explanation is : Correct Answer: A) Carbon Explanation: The isotope used as the standard for the relative mass scale of atoms is carbon-12 (\u00b9\u00b2C). The atomic [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-205724","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/205724","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=205724"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/205724\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=205724"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=205724"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=205724"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}