{"id":243422,"date":"2025-07-04T13:57:32","date_gmt":"2025-07-04T13:57:32","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=243422"},"modified":"2025-07-04T13:57:34","modified_gmt":"2025-07-04T13:57:34","slug":"which-molecule-is-a-stereoisomer-of-cis-2-pentene-2","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/04\/which-molecule-is-a-stereoisomer-of-cis-2-pentene-2\/","title":{"rendered":"Which molecule is a stereoisomer of cis-2-pentene"},"content":{"rendered":"\n

Which molecule is a stereoisomer of cis-2-pentene<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

The correct answer is C<\/strong>.<\/p>\n\n\n\n

Explanation<\/h3>\n\n\n\n

To identify a stereoisomer of cis<\/em>-2-pentene, we first need to understand the definitions of isomers and stereoisomers. Isomers are molecules that share the same molecular formula but have different arrangements of atoms. Stereoisomers are a specific type of isomer where the molecules have both the same molecular formula and the same connectivity (the sequence of bonded atoms), but they differ in the three-dimensional orientation of their atoms in space.<\/p>\n\n\n\n

Let’s analyze the starting molecule, cis<\/em>-2-pentene:<\/p>\n\n\n\n

    \n
  • “Pent”<\/strong>\u00a0indicates a chain of five carbon atoms.<\/li>\n\n\n\n
  • “ene”<\/strong>\u00a0signifies the presence of a carbon-carbon double bond.<\/li>\n\n\n\n
  • “2-“<\/strong>\u00a0specifies that the double bond is located between the second and third carbon atoms.<\/li>\n\n\n\n
  • The molecular formula for any pentene is C\u2085H\u2081\u2080.<\/li>\n\n\n\n
  • “cis”<\/strong>\u00a0describes the geometry around the double bond. It means that the two substituent groups on the carbons of the double bond (in this case, a methyl group on carbon 2 and an ethyl group on carbon 3) are positioned on the same side of the double bond.<\/li>\n<\/ul>\n\n\n\n

    A stereoisomer of cis<\/em>-2-pentene must therefore also be a 2-pentene molecule with the formula C\u2085H\u2081\u2080. The only difference will be its spatial arrangement. The alternative arrangement for a double bond is trans<\/em>, where the substituent groups are on opposite sides. Thus, we are looking for the structure of trans<\/em>-2-pentene.<\/p>\n\n\n\n

    Now let’s examine the given options:<\/p>\n\n\n\n

      \n
    • A. Pentane:<\/strong>\u00a0This molecule is an alkane, containing only single bonds. Its molecular formula is C\u2085H\u2081\u2082. Since its molecular formula is different from C\u2085H\u2081\u2080, it is not an isomer of 2-pentene.<\/li>\n\n\n\n
    • B. 1-Pentyne:<\/strong>\u00a0This molecule is an alkyne, containing a triple bond at the first carbon. Its molecular formula is C\u2085H\u2088. This formula is different from C\u2085H\u2081\u2080, so it cannot be an isomer of 2-pentene. Molecules with different formulas are simply different compounds.<\/li>\n\n\n\n
    • C.\u00a0trans<\/em>-2-Pentene:<\/strong>\u00a0This molecule has a five-carbon chain with a double bond between the second and third carbons. Its molecular formula is C\u2085H\u2081\u2080. The structure shows the methyl group (at C2) and the ethyl group (at C3) on opposite sides of the double bond. This is the definition of a\u00a0trans<\/em>\u00a0isomer. Since it has the same molecular formula and connectivity as\u00a0cis<\/em>-2-pentene but differs in its spatial geometry, it is a stereoisomer. Specifically,\u00a0cis<\/em>\u00a0and\u00a0trans<\/em>\u00a0isomers are a type of diastereomer known as geometric isomers.<\/li>\n\n\n\n
    • D. 2-Pentyne:<\/strong>\u00a0This molecule is an alkyne with a triple bond between the second and third carbons. Its molecular formula is C\u2085H\u2088. Like option B, it has a different molecular formula and is not an isomer of 2-pentene.<\/li>\n<\/ul>\n\n\n\n

      Therefore, the only molecule that fits the definition of a stereoisomer of cis<\/em>-2-pentene is option C, which is trans<\/em>-2-pentene.<\/p>\n\n\n\n

      \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

      Which molecule is a stereoisomer of cis-2-pentene The Correct Answer and Explanation is: The correct answer is C. Explanation To identify a stereoisomer of cis-2-pentene, we first need to understand the definitions of isomers and stereoisomers. Isomers are molecules that share the same molecular formula but have different arrangements of atoms. Stereoisomers are a specific type of […]<\/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-243422","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/243422","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=243422"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/243422\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=243422"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=243422"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=243422"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}