{"id":90720,"date":"2025-06-01T10:35:16","date_gmt":"2025-06-01T10:35:16","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=90720"},"modified":"2025-06-01T10:35:16","modified_gmt":"2025-06-01T10:35:16","slug":"calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/","title":{"rendered":"Calcium oxide reacts with water to produce slaked lime. It is an examp"},"content":{"rendered":"

Calcium oxide reacts with water to produce slaked lime. It is an example of<\/p>\n

[amp_mcq option1=”combination reaction” option2=”decomposition reaction” option3=”oxidation reaction” option4=”addition reaction” correct=”option1″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC CAPF – 2022<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nThe reaction described is between calcium oxide ($\\text{CaO}$) and water ($\\text{H}_2\\text{O}$) to produce slaked lime, which is calcium hydroxide ($\\text{Ca(OH)}_2$).
\nThe balanced chemical equation for this reaction is:
\n$\\text{CaO(s)} + \\text{H}_2\\text{O(l)} \\rightarrow \\text{Ca(OH)}_2\\text{(aq)}$<\/p>\n

Let’s analyze the types of reactions given in the options:
\nA) Combination reaction: A reaction in which two or more reactants combine to form a single product. In this reaction, calcium oxide and water (two reactants) combine to form calcium hydroxide (a single product). This matches the definition of a combination reaction.
\nB) Decomposition reaction: A reaction in which a single compound breaks down into two or more simpler substances. This is the opposite of the given reaction.
\nC) Oxidation reaction: A reaction involving the loss of electrons or increase in oxidation state. While redox aspects might be present in the formation of bonds, the primary classification based on the change in the number of substances is combination. The oxidation states of Ca (+2), O (-2), and H (+1) do not change overall.
\nD) Addition reaction: A reaction in which atoms are added to a molecule across a multiple bond (like a double or triple bond). This term is mainly used in organic chemistry for reactions involving unsaturated hydrocarbons. While water is added to CaO, the term ‘combination reaction’ is the standard classification for this type of inorganic reaction.<\/p>\n

The reaction fits perfectly the definition of a combination reaction. It is also a highly exothermic reaction, releasing a significant amount of heat, which is why it is also called the slaking of lime.
\n<\/section>\n

\n– Identifying the reactants and products of the reaction: Calcium oxide + Water -> Calcium hydroxide.
\n– Understanding the definition of different types of chemical reactions.
\n– Classifying the reaction based on the change in the number of reactants and products. Two reactants form one product, characteristic of a combination reaction.
\n<\/section>\n
\nThis reaction is a classic example of an inorganic combination reaction and the process of slaking quicklime ($\\text{CaO}$) to produce slaked lime ($\\text{Ca(OH)}_2$). Slaked lime has many uses, including in mortars, plasters, and water treatment. The reaction is also an example of a hydrolysis reaction because water is a reactant. However, among the given choices, “combination reaction” is the most appropriate primary classification.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

Calcium oxide reacts with water to produce slaked lime. It is an example of [amp_mcq option1=”combination reaction” option2=”decomposition reaction” option3=”oxidation reaction” option4=”addition reaction” correct=”option1″] This question was previously asked in UPSC CAPF – 2022 Download PDFAttempt Online The reaction described is between calcium oxide ($\\text{CaO}$) and water ($\\text{H}_2\\text{O}$) to produce slaked lime, which is calcium … <\/p>\n

Detailed SolutionCalcium oxide reacts with water to produce slaked lime. It is an examp<\/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":[1085],"tags":[1108,1096,1155],"class_list":["post-90720","post","type-post","status-publish","format-standard","hentry","category-upsc-capf","tag-1108","tag-chemistry","tag-physical-and-chemical-changes-solution","no-featured-image-padding"],"yoast_head":"\nCalcium oxide reacts with water to produce slaked lime. It is an examp<\/title>\n<meta name=\"description\" content=\"The reaction described is between calcium oxide ($text{CaO}$) and water ($text{H}_2text{O}$) to produce slaked lime, which is calcium hydroxide ($text{Ca(OH)}_2$). The balanced chemical equation for this reaction is: $text{CaO(s)} + text{H}_2text{O(l)} rightarrow text{Ca(OH)}_2text{(aq)}$ Let's analyze the types of reactions given in the options: A) Combination reaction: A reaction in which two or more reactants combine to form a single product. In this reaction, calcium oxide and water (two reactants) combine to form calcium hydroxide (a single product). This matches the definition of a combination reaction. B) Decomposition reaction: A reaction in which a single compound breaks down into two or more simpler substances. This is the opposite of the given reaction. C) Oxidation reaction: A reaction involving the loss of electrons or increase in oxidation state. While redox aspects might be present in the formation of bonds, the primary classification based on the change in the number of substances is combination. The oxidation states of Ca (+2), O (-2), and H (+1) do not change overall. D) Addition reaction: A reaction in which atoms are added to a molecule across a multiple bond (like a double or triple bond). This term is mainly used in organic chemistry for reactions involving unsaturated hydrocarbons. While water is added to CaO, the term 'combination reaction' is the standard classification for this type of inorganic reaction. The reaction fits perfectly the definition of a combination reaction. It is also a highly exothermic reaction, releasing a significant amount of heat, which is why it is also called the slaking of lime. - Identifying the reactants and products of the reaction: Calcium oxide + Water -> Calcium hydroxide. - Understanding the definition of different types of chemical reactions. - Classifying the reaction based on the change in the number of reactants and products. Two reactants form one product, characteristic of a combination reaction.\" \/>\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\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Calcium oxide reacts with water to produce slaked lime. It is an examp\" \/>\n<meta property=\"og:description\" content=\"The reaction described is between calcium oxide ($text{CaO}$) and water ($text{H}_2text{O}$) to produce slaked lime, which is calcium hydroxide ($text{Ca(OH)}_2$). The balanced chemical equation for this reaction is: $text{CaO(s)} + text{H}_2text{O(l)} rightarrow text{Ca(OH)}_2text{(aq)}$ Let's analyze the types of reactions given in the options: A) Combination reaction: A reaction in which two or more reactants combine to form a single product. In this reaction, calcium oxide and water (two reactants) combine to form calcium hydroxide (a single product). This matches the definition of a combination reaction. B) Decomposition reaction: A reaction in which a single compound breaks down into two or more simpler substances. This is the opposite of the given reaction. C) Oxidation reaction: A reaction involving the loss of electrons or increase in oxidation state. While redox aspects might be present in the formation of bonds, the primary classification based on the change in the number of substances is combination. The oxidation states of Ca (+2), O (-2), and H (+1) do not change overall. D) Addition reaction: A reaction in which atoms are added to a molecule across a multiple bond (like a double or triple bond). This term is mainly used in organic chemistry for reactions involving unsaturated hydrocarbons. While water is added to CaO, the term 'combination reaction' is the standard classification for this type of inorganic reaction. The reaction fits perfectly the definition of a combination reaction. It is also a highly exothermic reaction, releasing a significant amount of heat, which is why it is also called the slaking of lime. - Identifying the reactants and products of the reaction: Calcium oxide + Water -> Calcium hydroxide. - Understanding the definition of different types of chemical reactions. - Classifying the reaction based on the change in the number of reactants and products. Two reactants form one product, characteristic of a combination reaction.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T10:35:16+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":"Calcium oxide reacts with water to produce slaked lime. It is an examp","description":"The reaction described is between calcium oxide ($text{CaO}$) and water ($text{H}_2text{O}$) to produce slaked lime, which is calcium hydroxide ($text{Ca(OH)}_2$). The balanced chemical equation for this reaction is: $text{CaO(s)} + text{H}_2text{O(l)} rightarrow text{Ca(OH)}_2text{(aq)}$ Let's analyze the types of reactions given in the options: A) Combination reaction: A reaction in which two or more reactants combine to form a single product. In this reaction, calcium oxide and water (two reactants) combine to form calcium hydroxide (a single product). This matches the definition of a combination reaction. B) Decomposition reaction: A reaction in which a single compound breaks down into two or more simpler substances. This is the opposite of the given reaction. C) Oxidation reaction: A reaction involving the loss of electrons or increase in oxidation state. While redox aspects might be present in the formation of bonds, the primary classification based on the change in the number of substances is combination. The oxidation states of Ca (+2), O (-2), and H (+1) do not change overall. D) Addition reaction: A reaction in which atoms are added to a molecule across a multiple bond (like a double or triple bond). This term is mainly used in organic chemistry for reactions involving unsaturated hydrocarbons. While water is added to CaO, the term 'combination reaction' is the standard classification for this type of inorganic reaction. The reaction fits perfectly the definition of a combination reaction. It is also a highly exothermic reaction, releasing a significant amount of heat, which is why it is also called the slaking of lime. - Identifying the reactants and products of the reaction: Calcium oxide + Water -> Calcium hydroxide. - Understanding the definition of different types of chemical reactions. - Classifying the reaction based on the change in the number of reactants and products. Two reactants form one product, characteristic of a combination reaction.","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\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/","og_locale":"en_US","og_type":"article","og_title":"Calcium oxide reacts with water to produce slaked lime. 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While redox aspects might be present in the formation of bonds, the primary classification based on the change in the number of substances is combination. The oxidation states of Ca (+2), O (-2), and H (+1) do not change overall. D) Addition reaction: A reaction in which atoms are added to a molecule across a multiple bond (like a double or triple bond). This term is mainly used in organic chemistry for reactions involving unsaturated hydrocarbons. While water is added to CaO, the term 'combination reaction' is the standard classification for this type of inorganic reaction. The reaction fits perfectly the definition of a combination reaction. It is also a highly exothermic reaction, releasing a significant amount of heat, which is why it is also called the slaking of lime. - Identifying the reactants and products of the reaction: Calcium oxide + Water -> Calcium hydroxide. - Understanding the definition of different types of chemical reactions. - Classifying the reaction based on the change in the number of reactants and products. Two reactants form one product, characteristic of a combination reaction.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T10:35:16+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\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/","url":"https:\/\/exam.pscnotes.com\/mcq\/calcium-oxide-reacts-with-water-to-produce-slaked-lime-it-is-an-examp\/","name":"Calcium oxide reacts with water to produce slaked lime. 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B) Decomposition reaction: A reaction in which a single compound breaks down into two or more simpler substances. This is the opposite of the given reaction. C) Oxidation reaction: A reaction involving the loss of electrons or increase in oxidation state. While redox aspects might be present in the formation of bonds, the primary classification based on the change in the number of substances is combination. The oxidation states of Ca (+2), O (-2), and H (+1) do not change overall. D) Addition reaction: A reaction in which atoms are added to a molecule across a multiple bond (like a double or triple bond). This term is mainly used in organic chemistry for reactions involving unsaturated hydrocarbons. While water is added to CaO, the term 'combination reaction' is the standard classification for this type of inorganic reaction. The reaction fits perfectly the definition of a combination reaction. It is also a highly exothermic reaction, releasing a significant amount of heat, which is why it is also called the slaking of lime. - Identifying the reactants and products of the reaction: Calcium oxide + Water -> Calcium hydroxide. - Understanding the definition of different types of chemical reactions. - Classifying the reaction based on the change in the number of reactants and products. 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