{"id":84906,"date":"2025-06-01T02:55:15","date_gmt":"2025-06-01T02:55:15","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=84906"},"modified":"2025-06-01T02:55:15","modified_gmt":"2025-06-01T02:55:15","slug":"which-one-of-the-following-elements-cannot-be-detected-by-lassaignes","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/","title":{"rendered":"Which one of the following elements cannot be detected by “Lassaigne’s"},"content":{"rendered":"

Which one of the following elements cannot be detected by “Lassaigne’s test”?<\/p>\n

[amp_mcq option1=”I” option2=”Cl” option3=”S” option4=”F” correct=”option4″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC CDS-1 – 2019<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nLassaigne’s test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic compound. The organic substance is fused with metallic sodium, converting these elements into ionic compounds (e.g., NaCN, Na2S, NaCl, NaBr, NaI) which are then extracted with water and tested for using specific reagents. Fluorine (F) is a halogen, but Lassaigne’s test is generally not used or is unreliable for its detection because sodium fluoride (NaF) is less soluble than other sodium halides, and organic fluoro compounds may not completely decompose to ionic fluoride upon fusion. Therefore, fluorine cannot be reliably detected by Lassaigne’s test.
\n<\/section>\n
\n– Lassaigne’s test detects N, S, Cl, Br, and I in organic compounds.
\n– Fluorine (F) is typically not detectable by Lassaigne’s test due to difficulties in forming and dissolving ionic fluoride.
\n<\/section>\n
\nFor detecting fluorine in organic compounds, alternative methods like combustion followed by fluoride ion-selective electrode measurement or gravimetric analysis as calcium fluoride are used.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

Which one of the following elements cannot be detected by “Lassaigne’s test”? [amp_mcq option1=”I” option2=”Cl” option3=”S” option4=”F” correct=”option4″] This question was previously asked in UPSC CDS-1 – 2019 Download PDFAttempt Online Lassaigne’s test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic … <\/p>\n

Detailed SolutionWhich one of the following elements cannot be detected by “Lassaigne’s<\/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":[1087],"tags":[1119,1096,1272],"class_list":["post-84906","post","type-post","status-publish","format-standard","hentry","category-upsc-cds-1","tag-1119","tag-chemistry","tag-organic-chemistry","no-featured-image-padding"],"yoast_head":"\nWhich one of the following elements cannot be detected by "Lassaigne's<\/title>\n<meta name=\"description\" content=\"Lassaigne's test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic compound. The organic substance is fused with metallic sodium, converting these elements into ionic compounds (e.g., NaCN, Na2S, NaCl, NaBr, NaI) which are then extracted with water and tested for using specific reagents. Fluorine (F) is a halogen, but Lassaigne's test is generally not used or is unreliable for its detection because sodium fluoride (NaF) is less soluble than other sodium halides, and organic fluoro compounds may not completely decompose to ionic fluoride upon fusion. Therefore, fluorine cannot be reliably detected by Lassaigne's test. - Lassaigne's test detects N, S, Cl, Br, and I in organic compounds. - Fluorine (F) is typically not detectable by Lassaigne's test due to difficulties in forming and dissolving ionic fluoride.\" \/>\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-elements-cannot-be-detected-by-lassaignes\/\" \/>\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 elements cannot be detected by "Lassaigne's\" \/>\n<meta property=\"og:description\" content=\"Lassaigne's test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic compound. The organic substance is fused with metallic sodium, converting these elements into ionic compounds (e.g., NaCN, Na2S, NaCl, NaBr, NaI) which are then extracted with water and tested for using specific reagents. Fluorine (F) is a halogen, but Lassaigne's test is generally not used or is unreliable for its detection because sodium fluoride (NaF) is less soluble than other sodium halides, and organic fluoro compounds may not completely decompose to ionic fluoride upon fusion. Therefore, fluorine cannot be reliably detected by Lassaigne's test. - Lassaigne's test detects N, S, Cl, Br, and I in organic compounds. - Fluorine (F) is typically not detectable by Lassaigne's test due to difficulties in forming and dissolving ionic fluoride.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T02:55:15+00:00\" \/>\n<meta name=\"author\" content=\"rawan239\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"rawan239\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Which one of the following elements cannot be detected by \"Lassaigne's","description":"Lassaigne's test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic compound. The organic substance is fused with metallic sodium, converting these elements into ionic compounds (e.g., NaCN, Na2S, NaCl, NaBr, NaI) which are then extracted with water and tested for using specific reagents. Fluorine (F) is a halogen, but Lassaigne's test is generally not used or is unreliable for its detection because sodium fluoride (NaF) is less soluble than other sodium halides, and organic fluoro compounds may not completely decompose to ionic fluoride upon fusion. Therefore, fluorine cannot be reliably detected by Lassaigne's test. - Lassaigne's test detects N, S, Cl, Br, and I in organic compounds. - Fluorine (F) is typically not detectable by Lassaigne's test due to difficulties in forming and dissolving ionic fluoride.","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-elements-cannot-be-detected-by-lassaignes\/","og_locale":"en_US","og_type":"article","og_title":"Which one of the following elements cannot be detected by \"Lassaigne's","og_description":"Lassaigne's test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic compound. The organic substance is fused with metallic sodium, converting these elements into ionic compounds (e.g., NaCN, Na2S, NaCl, NaBr, NaI) which are then extracted with water and tested for using specific reagents. Fluorine (F) is a halogen, but Lassaigne's test is generally not used or is unreliable for its detection because sodium fluoride (NaF) is less soluble than other sodium halides, and organic fluoro compounds may not completely decompose to ionic fluoride upon fusion. Therefore, fluorine cannot be reliably detected by Lassaigne's test. - Lassaigne's test detects N, S, Cl, Br, and I in organic compounds. - Fluorine (F) is typically not detectable by Lassaigne's test due to difficulties in forming and dissolving ionic fluoride.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T02:55:15+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/","url":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/","name":"Which one of the following elements cannot be detected by \"Lassaigne's","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T02:55:15+00:00","dateModified":"2025-06-01T02:55:15+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"Lassaigne's test (Sodium Fusion Test) is used to detect the presence of elements like nitrogen, sulfur, and halogens (chlorine, bromine, iodine) in an organic compound. 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Therefore, fluorine cannot be reliably detected by Lassaigne's test. - Lassaigne's test detects N, S, Cl, Br, and I in organic compounds. - Fluorine (F) is typically not detectable by Lassaigne's test due to difficulties in forming and dissolving ionic fluoride.","breadcrumb":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-elements-cannot-be-detected-by-lassaignes\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/exam.pscnotes.com\/mcq\/"},{"@type":"ListItem","position":2,"name":"UPSC CDS-1","item":"https:\/\/exam.pscnotes.com\/mcq\/category\/upsc-cds-1\/"},{"@type":"ListItem","position":3,"name":"Which one of the following elements cannot be detected by “Lassaigne’s"}]},{"@type":"WebSite","@id":"https:\/\/exam.pscnotes.com\/mcq\/#website","url":"https:\/\/exam.pscnotes.com\/mcq\/","name":"MCQ and Quiz for Exams","description":"","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/exam.pscnotes.com\/mcq\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209","name":"rawan239","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","caption":"rawan239"},"sameAs":["https:\/\/exam.pscnotes.com"],"url":"https:\/\/exam.pscnotes.com\/mcq\/author\/rawan239\/"}]}},"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/84906","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/comments?post=84906"}],"version-history":[{"count":0,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/84906\/revisions"}],"wp:attachment":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/media?parent=84906"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/categories?post=84906"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/tags?post=84906"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}