{"id":87694,"date":"2025-06-01T06:51:24","date_gmt":"2025-06-01T06:51:24","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=87694"},"modified":"2025-06-01T06:51:24","modified_gmt":"2025-06-01T06:51:24","slug":"which-one-of-the-following-statements-regarding-a-thermos-flask-is-not","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/","title":{"rendered":"Which one of the following statements regarding a thermos flask is NOT"},"content":{"rendered":"

Which one of the following statements regarding a thermos flask is NOT correct?<\/p>\n

[amp_mcq option1=”The walls of flask are separated by vacuum and made of glass which is a poor conductor of heat” option2=”The glass walls themselves have shiny surfaces” option3=”The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall” option4=”The cork supports are poor conductors of heat” correct=”option3″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC NDA-1 – 2019<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nThe correct option is C) The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall. This statement is NOT correct regarding a thermos flask.
\n<\/section>\n
\n– A thermos flask is designed to minimize heat transfer by conduction, convection, and radiation.
\n– To minimize heat transfer by radiation, the surfaces of the inner and outer glass walls are made shiny (often silvered). Shiny surfaces are poor emitters and poor absorbers of thermal radiation.
\n– Statement A is correct: Vacuum between walls minimizes conduction and convection; glass is a poor conductor.
\n– Statement B is correct: The glass walls have shiny surfaces to reduce radiation.
\n– Statement D is correct: Cork or plastic supports minimize conduction through the neck.
\n– Statement C is incorrect because the shiny inner wall surface is designed to radiate a *poor* amount (low emissivity) of heat, not a “good amount”. While the outer wall would absorb some radiated heat, the primary mechanism to reduce radiative transfer is the low emissivity\/absorptivity of the surfaces.
\n<\/section>\n
\nHeat transfer in a thermos flask is minimized through several features: vacuum (prevents conduction\/convection), silvered\/shiny surfaces (reduces radiation), poor conducting stopper (prevents conduction\/convection), and supports made of insulating material (prevents conduction). The effectiveness relies on minimizing all three modes of heat transfer.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

Which one of the following statements regarding a thermos flask is NOT correct? [amp_mcq option1=”The walls of flask are separated by vacuum and made of glass which is a poor conductor of heat” option2=”The glass walls themselves have shiny surfaces” option3=”The surface of inner wall radiates good amount of heat and the surface of outer … <\/p>\n

Detailed SolutionWhich one of the following statements regarding a thermos flask is NOT<\/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":[1093],"tags":[1119,1130,1128],"class_list":["post-87694","post","type-post","status-publish","format-standard","hentry","category-upsc-nda-1","tag-1119","tag-heat-and-thermodynamics","tag-physics","no-featured-image-padding"],"yoast_head":"\nWhich one of the following statements regarding a thermos flask is NOT<\/title>\n<meta name=\"description\" content=\"The correct option is C) The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall. This statement is NOT correct regarding a thermos flask. - A thermos flask is designed to minimize heat transfer by conduction, convection, and radiation. - To minimize heat transfer by radiation, the surfaces of the inner and outer glass walls are made shiny (often silvered). Shiny surfaces are poor emitters and poor absorbers of thermal radiation. - Statement A is correct: Vacuum between walls minimizes conduction and convection; glass is a poor conductor. - Statement B is correct: The glass walls have shiny surfaces to reduce radiation. - Statement D is correct: Cork or plastic supports minimize conduction through the neck. - Statement C is incorrect because the shiny inner wall surface is designed to radiate a *poor* amount (low emissivity) of heat, not a "good amount". While the outer wall would absorb some radiated heat, the primary mechanism to reduce radiative transfer is the low emissivity\/absorptivity of the surfaces.\" \/>\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-statements-regarding-a-thermos-flask-is-not\/\" \/>\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 statements regarding a thermos flask is NOT\" \/>\n<meta property=\"og:description\" content=\"The correct option is C) The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall. This statement is NOT correct regarding a thermos flask. - A thermos flask is designed to minimize heat transfer by conduction, convection, and radiation. - To minimize heat transfer by radiation, the surfaces of the inner and outer glass walls are made shiny (often silvered). Shiny surfaces are poor emitters and poor absorbers of thermal radiation. - Statement A is correct: Vacuum between walls minimizes conduction and convection; glass is a poor conductor. - Statement B is correct: The glass walls have shiny surfaces to reduce radiation. - Statement D is correct: Cork or plastic supports minimize conduction through the neck. - Statement C is incorrect because the shiny inner wall surface is designed to radiate a *poor* amount (low emissivity) of heat, not a "good amount". While the outer wall would absorb some radiated heat, the primary mechanism to reduce radiative transfer is the low emissivity\/absorptivity of the surfaces.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T06:51:24+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=\"2 minutes\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Which one of the following statements regarding a thermos flask is NOT","description":"The correct option is C) The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall. This statement is NOT correct regarding a thermos flask. - A thermos flask is designed to minimize heat transfer by conduction, convection, and radiation. - To minimize heat transfer by radiation, the surfaces of the inner and outer glass walls are made shiny (often silvered). Shiny surfaces are poor emitters and poor absorbers of thermal radiation. - Statement A is correct: Vacuum between walls minimizes conduction and convection; glass is a poor conductor. - Statement B is correct: The glass walls have shiny surfaces to reduce radiation. - Statement D is correct: Cork or plastic supports minimize conduction through the neck. - Statement C is incorrect because the shiny inner wall surface is designed to radiate a *poor* amount (low emissivity) of heat, not a \"good amount\". While the outer wall would absorb some radiated heat, the primary mechanism to reduce radiative transfer is the low emissivity\/absorptivity of the surfaces.","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-statements-regarding-a-thermos-flask-is-not\/","og_locale":"en_US","og_type":"article","og_title":"Which one of the following statements regarding a thermos flask is NOT","og_description":"The correct option is C) The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall. This statement is NOT correct regarding a thermos flask. - A thermos flask is designed to minimize heat transfer by conduction, convection, and radiation. - To minimize heat transfer by radiation, the surfaces of the inner and outer glass walls are made shiny (often silvered). Shiny surfaces are poor emitters and poor absorbers of thermal radiation. - Statement A is correct: Vacuum between walls minimizes conduction and convection; glass is a poor conductor. - Statement B is correct: The glass walls have shiny surfaces to reduce radiation. - Statement D is correct: Cork or plastic supports minimize conduction through the neck. - Statement C is incorrect because the shiny inner wall surface is designed to radiate a *poor* amount (low emissivity) of heat, not a \"good amount\". While the outer wall would absorb some radiated heat, the primary mechanism to reduce radiative transfer is the low emissivity\/absorptivity of the surfaces.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T06:51:24+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/","url":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/","name":"Which one of the following statements regarding a thermos flask is NOT","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T06:51:24+00:00","dateModified":"2025-06-01T06:51:24+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"The correct option is C) The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of heat that is radiated from the inner wall. This statement is NOT correct regarding a thermos flask. - A thermos flask is designed to minimize heat transfer by conduction, convection, and radiation. - To minimize heat transfer by radiation, the surfaces of the inner and outer glass walls are made shiny (often silvered). Shiny surfaces are poor emitters and poor absorbers of thermal radiation. - Statement A is correct: Vacuum between walls minimizes conduction and convection; glass is a poor conductor. - Statement B is correct: The glass walls have shiny surfaces to reduce radiation. - Statement D is correct: Cork or plastic supports minimize conduction through the neck. - Statement C is incorrect because the shiny inner wall surface is designed to radiate a *poor* amount (low emissivity) of heat, not a \"good amount\". While the outer wall would absorb some radiated heat, the primary mechanism to reduce radiative transfer is the low emissivity\/absorptivity of the surfaces.","breadcrumb":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-one-of-the-following-statements-regarding-a-thermos-flask-is-not\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/exam.pscnotes.com\/mcq\/"},{"@type":"ListItem","position":2,"name":"UPSC NDA-1","item":"https:\/\/exam.pscnotes.com\/mcq\/category\/upsc-nda-1\/"},{"@type":"ListItem","position":3,"name":"Which one of the following statements regarding a thermos flask is NOT"}]},{"@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\/87694","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=87694"}],"version-history":[{"count":0,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/87694\/revisions"}],"wp:attachment":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/media?parent=87694"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/categories?post=87694"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/tags?post=87694"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}