{"id":183228,"date":"2025-01-16T05:54:31","date_gmt":"2025-01-16T05:54:31","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=183228"},"modified":"2025-01-16T05:54:33","modified_gmt":"2025-01-16T05:54:33","slug":"boron-which-has-an-average-atomic-mass-of-10-81-amu","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/01\/16\/boron-which-has-an-average-atomic-mass-of-10-81-amu\/","title":{"rendered":"Boron, which has an average atomic mass of 10.81 amu"},"content":{"rendered":"\n<p>Boron, which has an average atomic mass of 10.81 amu, has two stable isotopes: boron-10 and boron-11. Boron-10 has an atomic mass of 10.0129 amu and a natural abundance of 19.78%. What is the atomic mass of boron-11?<\/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<p>To calculate the atomic mass of boron-11, we use the concept of the weighted average atomic mass based on the natural abundances of the isotopes.<\/p>\n\n\n\n<p>Given:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The atomic mass of boron-10 (B-10) is 10.0129 amu, and its natural abundance is 19.78% (or 0.1978 in decimal form).<\/li>\n\n\n\n<li>The average atomic mass of boron is 10.81 amu.<\/li>\n\n\n\n<li>The remaining natural abundance of boron must be the abundance of boron-11 (B-11). Since the total abundance must add up to 100%, the natural abundance of boron-11 is 100% &#8211; 19.78% = 80.22% (or 0.8022 in decimal form).<\/li>\n<\/ul>\n\n\n\n<p>Let\u2019s define the atomic mass of boron-11 as ( x ). The weighted average atomic mass formula for boron is:<\/p>\n\n\n\n<p>[<br>\\text{Average Atomic Mass} = ( \\text{atomic mass of B-10} \\times \\text{abundance of B-10} ) + ( \\text{atomic mass of B-11} \\times \\text{abundance of B-11} )<br>]<\/p>\n\n\n\n<p>Substituting the known values:<\/p>\n\n\n\n<p>[<br>10.81 = (10.0129 \\times 0.1978) + (x \\times 0.8022)<br>]<\/p>\n\n\n\n<p>First, calculate the contribution from boron-10:<\/p>\n\n\n\n<p>[<br>10.0129 \\times 0.1978 = 1.9801<br>]<\/p>\n\n\n\n<p>Now substitute into the equation:<\/p>\n\n\n\n<p>[<br>10.81 = 1.9801 + (x \\times 0.8022)<br>]<\/p>\n\n\n\n<p>Next, isolate ( x ):<\/p>\n\n\n\n<p>[<br>10.81 &#8211; 1.9801 = x \\times 0.8022<br>]<\/p>\n\n\n\n<p>[<br>8.8299 = x \\times 0.8022<br>]<\/p>\n\n\n\n<p>Finally, solve for ( x ):<\/p>\n\n\n\n<p>[<br>x = \\frac{8.8299}{0.8022} \\approx 11.01<br>]<\/p>\n\n\n\n<p>Thus, the atomic mass of boron-11 is approximately <strong>11.01 amu<\/strong>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Explanation:<\/h3>\n\n\n\n<p>The average atomic mass of an element is the weighted sum of the masses of its isotopes, with each mass multiplied by the fraction of the element&#8217;s occurrence in nature. Boron-10 and boron-11 have different atomic masses and natural abundances. By setting up the equation based on these quantities, we can solve for the unknown atomic mass of boron-11. This calculation demonstrates how isotope abundance and mass contribute to an element\u2019s average atomic mass, providing an essential understanding of atomic structure and properties.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Boron, which has an average atomic mass of 10.81 amu, has two stable isotopes: boron-10 and boron-11. Boron-10 has an atomic mass of 10.0129 amu and a natural abundance of 19.78%. What is the atomic mass of boron-11? The Correct Answer and Explanation is : To calculate the atomic mass of boron-11, we use the [&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-183228","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/183228","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=183228"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/183228\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=183228"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=183228"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=183228"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}