{"id":84989,"date":"2025-06-01T02:59:11","date_gmt":"2025-06-01T02:59:11","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=84989"},"modified":"2025-06-01T02:59:11","modified_gmt":"2025-06-01T02:59:11","slug":"when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/","title":{"rendered":"When air is blown from mouth into a test tube containing limewater, th"},"content":{"rendered":"

When air is blown from mouth into a test tube containing limewater, the limewater turns milky. This is due to the presence of<\/p>\n

[amp_mcq option1=”water vapour” option2=”oxygen” option3=”carbon dioxide” option4=”carbon monoxide” correct=”option3″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC CDS-1 – 2020<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nLimewater is a solution of calcium hydroxide (Ca(OH)\u2082). When carbon dioxide (CO\u2082) is passed through limewater, it reacts to form insoluble calcium carbonate (CaCO\u2083), which precipitates out of the solution, causing it to turn milky or cloudy. Human exhaled air contains a higher concentration of carbon dioxide compared to inhaled air.
\n<\/section>\n
\n– Limewater (Calcium hydroxide solution) is a test for carbon dioxide.
\n– The reaction is: Ca(OH)\u2082(aq) + CO\u2082(g) \u2192 CaCO\u2083(s) + H\u2082O(l).
\n– Calcium carbonate (CaCO\u2083) is insoluble, causing the milky appearance.
\n– Human breath contains significant amounts of carbon dioxide.
\n<\/section>\n
\nThe reaction is reversible. If excess carbon dioxide is passed through the milky solution, the calcium carbonate can react further with water and carbon dioxide to form soluble calcium bicarbonate (Ca(HCO\u2083)\u2082), causing the milkiness to disappear.
\nCaCO\u2083(s) + H\u2082O(l) + CO\u2082(g) \u2192 Ca(HCO\u2083)\u2082(aq)
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

When air is blown from mouth into a test tube containing limewater, the limewater turns milky. This is due to the presence of [amp_mcq option1=”water vapour” option2=”oxygen” option3=”carbon dioxide” option4=”carbon monoxide” correct=”option3″] This question was previously asked in UPSC CDS-1 – 2020 Download PDFAttempt Online Limewater is a solution of calcium hydroxide (Ca(OH)\u2082). When carbon … <\/p>\n

Detailed SolutionWhen air is blown from mouth into a test tube containing limewater, th<\/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":[1288,1202,1096],"class_list":["post-84989","post","type-post","status-publish","format-standard","hentry","category-upsc-cds-1","tag-1288","tag-acid-base-and-salt","tag-chemistry","no-featured-image-padding"],"yoast_head":"\nWhen air is blown from mouth into a test tube containing limewater, th<\/title>\n<meta name=\"description\" content=\"Limewater is a solution of calcium hydroxide (Ca(OH)\u2082). When carbon dioxide (CO\u2082) is passed through limewater, it reacts to form insoluble calcium carbonate (CaCO\u2083), which precipitates out of the solution, causing it to turn milky or cloudy. Human exhaled air contains a higher concentration of carbon dioxide compared to inhaled air. - Limewater (Calcium hydroxide solution) is a test for carbon dioxide. - The reaction is: Ca(OH)\u2082(aq) + CO\u2082(g) \u2192 CaCO\u2083(s) + H\u2082O(l). - Calcium carbonate (CaCO\u2083) is insoluble, causing the milky appearance. - Human breath contains significant amounts of carbon dioxide.\" \/>\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\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"When air is blown from mouth into a test tube containing limewater, th\" \/>\n<meta property=\"og:description\" content=\"Limewater is a solution of calcium hydroxide (Ca(OH)\u2082). When carbon dioxide (CO\u2082) is passed through limewater, it reacts to form insoluble calcium carbonate (CaCO\u2083), which precipitates out of the solution, causing it to turn milky or cloudy. Human exhaled air contains a higher concentration of carbon dioxide compared to inhaled air. - Limewater (Calcium hydroxide solution) is a test for carbon dioxide. - The reaction is: Ca(OH)\u2082(aq) + CO\u2082(g) \u2192 CaCO\u2083(s) + H\u2082O(l). - Calcium carbonate (CaCO\u2083) is insoluble, causing the milky appearance. - Human breath contains significant amounts of carbon dioxide.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T02:59:11+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":"When air is blown from mouth into a test tube containing limewater, th","description":"Limewater is a solution of calcium hydroxide (Ca(OH)\u2082). When carbon dioxide (CO\u2082) is passed through limewater, it reacts to form insoluble calcium carbonate (CaCO\u2083), which precipitates out of the solution, causing it to turn milky or cloudy. Human exhaled air contains a higher concentration of carbon dioxide compared to inhaled air. - Limewater (Calcium hydroxide solution) is a test for carbon dioxide. - The reaction is: Ca(OH)\u2082(aq) + CO\u2082(g) \u2192 CaCO\u2083(s) + H\u2082O(l). - Calcium carbonate (CaCO\u2083) is insoluble, causing the milky appearance. - Human breath contains significant amounts of carbon dioxide.","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\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/","og_locale":"en_US","og_type":"article","og_title":"When air is blown from mouth into a test tube containing limewater, th","og_description":"Limewater is a solution of calcium hydroxide (Ca(OH)\u2082). When carbon dioxide (CO\u2082) is passed through limewater, it reacts to form insoluble calcium carbonate (CaCO\u2083), which precipitates out of the solution, causing it to turn milky or cloudy. Human exhaled air contains a higher concentration of carbon dioxide compared to inhaled air. - Limewater (Calcium hydroxide solution) is a test for carbon dioxide. - The reaction is: Ca(OH)\u2082(aq) + CO\u2082(g) \u2192 CaCO\u2083(s) + H\u2082O(l). - Calcium carbonate (CaCO\u2083) is insoluble, causing the milky appearance. - Human breath contains significant amounts of carbon dioxide.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T02:59:11+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\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/","url":"https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/","name":"When air is blown from mouth into a test tube containing limewater, th","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T02:59:11+00:00","dateModified":"2025-06-01T02:59:11+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"Limewater is a solution of calcium hydroxide (Ca(OH)\u2082). 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Human exhaled air contains a higher concentration of carbon dioxide compared to inhaled air. - Limewater (Calcium hydroxide solution) is a test for carbon dioxide. - The reaction is: Ca(OH)\u2082(aq) + CO\u2082(g) \u2192 CaCO\u2083(s) + H\u2082O(l). - Calcium carbonate (CaCO\u2083) is insoluble, causing the milky appearance. - Human breath contains significant amounts of carbon dioxide.","breadcrumb":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/exam.pscnotes.com\/mcq\/when-air-is-blown-from-mouth-into-a-test-tube-containing-limewater-th\/#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":"When air is blown from mouth into a test tube containing limewater, th"}]},{"@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\/84989","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=84989"}],"version-history":[{"count":0,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/84989\/revisions"}],"wp:attachment":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/media?parent=84989"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/categories?post=84989"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/tags?post=84989"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}