{"id":2521,"date":"2026-05-28T17:13:15","date_gmt":"2026-05-28T11:43:15","guid":{"rendered":"https:\/\/mymockmate.com\/notes\/?p=2521"},"modified":"2026-05-28T17:13:18","modified_gmt":"2026-05-28T11:43:18","slug":"ncert-class-9-science-atomic-foundations-of-matter-solutions","status":"publish","type":"post","link":"https:\/\/mymockmate.com\/notes\/ncert-class-9-science-atomic-foundations-of-matter-solutions\/","title":{"rendered":"NCERT Class 9 Science Atomic Foundations of Matter  Solutions"},"content":{"rendered":"<div class=\"pdfprnt-buttons pdfprnt-buttons-post pdfprnt-top-bottom-right\"><a href=\"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/posts\/2521?print=print\" class=\"pdfprnt-button pdfprnt-button-print\" target=\"_blank\" ><img decoding=\"async\" src=\"https:\/\/mymockmate.com\/notes\/wp-content\/plugins\/pdf-print\/images\/print.png\" alt=\"image_print\" title=\"Print Content\" \/><span class=\"pdfprnt-button-title pdfprnt-button-print-title\">Print<\/span><\/a> <span class=\"pdfprnt-count-generation\"><\/span><\/div>\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Short Intro<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">This chapter introduces the atomic nature of matter and explains how atoms combine to form molecules and compounds. Students learn important laws of chemistry, chemical bonding, writing chemical formulae, ionic and covalent compounds, and molecular mass through solved examples and numerical problems.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Quick Information Box<\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Topic<\/th><th>Details<\/th><\/tr><\/thead><tbody><tr><td>Chapter<\/td><td>Atomic Foundations of Matter<\/td><\/tr><tr><td>Class<\/td><td>Grade 9<\/td><\/tr><tr><td>Subject<\/td><td>Science<\/td><\/tr><tr><td>Main Topics<\/td><td>Chemical Bonding, Atoms, Molecules<\/td><\/tr><tr><td>Important Laws<\/td><td>Conservation of Mass, Constant Proportions<\/td><\/tr><tr><td>Key Bond Types<\/td><td>Ionic Bond and Covalent Bond<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h1 class=\"wp-block-heading\">Concepts Used (Topics Covered)<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Law of Conservation of Mass<\/li>\n\n\n\n<li>Law of Constant Proportions<\/li>\n\n\n\n<li>Dalton\u2019s Atomic Theory<\/li>\n\n\n\n<li>Molecules and Chemical Bonds<\/li>\n\n\n\n<li>Covalent Bond Formation<\/li>\n\n\n\n<li>Ionic Bond Formation<\/li>\n\n\n\n<li>Cations and Anions<\/li>\n\n\n\n<li>Writing Chemical Formulae<\/li>\n\n\n\n<li>Properties of Ionic and Covalent Compounds<\/li>\n\n\n\n<li>Molecular Mass<\/li>\n\n\n\n<li>Formula Unit Mass<\/li>\n<\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">Important Formulas<\/h1>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Mass of Reactants = Mass of Products<\/li>\n\n\n\n<li>Number of Neutrons<br>= Mass Number \u2212 Atomic Number<\/li>\n\n\n\n<li>Molecular Mass<br>= Sum of Atomic Masses of All Atoms<\/li>\n\n\n\n<li>Formula Unit Mass<br>= Sum of Atomic Masses in Ionic Compound<\/li>\n\n\n\n<li>Chemical Formula by Criss-cross Method<\/li>\n<\/ol>\n\n\n\n<h1 class=\"wp-block-heading\">Questions &amp; Step-by-step Solutions with Explanation<\/h1>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q1. Law of Conservation of Mass<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Question:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A student burns ethanol in an open beaker and no residue remains. Is the law violated?<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. During burning, gases like carbon dioxide and water vapour escape into air. Total mass remains conserved when gases are included.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Law of Conservation of Mass is not violated.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q2. Water Formation Problem<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Question:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">20 g hydrogen reacts completely with 160 g oxygen. Find mass of water formed.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">According to Law of Conservation of Mass:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Mass of reactants = Mass of products<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 20 + 160<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 180 g<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">180 g water is formed.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q3. Sodium Chloride Ratio Problem<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Question:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">NaCl contains sodium and chlorine in ratio 23 : 35.5. If 46 g sodium reacts, how much chlorine is required?<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">23 g sodium reacts with 35.5 g chlorine<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">46 g sodium reacts with:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= (35.5 \u00d7 46) \/ 23<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 71 g<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">71 g chlorine is needed.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q4. Sulfur and Oxygen Compound<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Question:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Compound contains 40% sulfur and 60% oxygen. If sulfur = 20 g, find oxygen mass.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Sulfur : Oxygen = 40 : 60<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">20 : x = 40 : 60<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">x = (20 \u00d7 60)\/40<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 30 g<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">30 g oxygen<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q5. Carbon Monoxide Formation<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Question:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">CO contains carbon and oxygen in ratio 3 : 4. Find oxygen needed for 9 g carbon.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">3 g carbon combines with 4 g oxygen<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">9 g carbon combines with:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= (4 \u00d7 9)\/3<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 12 g<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">12 g oxygen<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q6. Dalton\u2019s Atomic Theory Assertion<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Assertion:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">2 g hydrogen combines with 16 g oxygen to form 18 g water.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Reason:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Atoms combine in simple whole number ratios.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Both are true and Reason correctly explains Assertion.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q7. Formation of Hydrogen Molecule<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Each hydrogen atom has 1 electron.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Two hydrogen atoms share one electron each to complete duplet.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">H \u2014 H<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Bond Type:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Single Covalent Bond<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q8. Formation of Chlorine Molecule<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Each chlorine atom has 7 valence electrons.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">They share one electron pair to complete octet.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cl \u2014 Cl<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Bond Type:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Single Covalent Bond<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q9. Formation of Oxygen Molecule<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Oxygen has 6 valence electrons.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Each oxygen atom shares 2 electrons.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">O = O<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Bond Type:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Double Covalent Bond<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q10. Formation of Water Molecule<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Oxygen needs 2 electrons.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Two hydrogen atoms share one electron each with oxygen.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Structure:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">H \u2014 O \u2014 H<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Formula:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">H\u2082O<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q11. Why Neon Does Not React<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Neon has complete octet configuration.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore it is chemically stable and neither gains nor loses electrons.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q12. Formation of Sodium Chloride<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Sodium loses one electron \u2192 Na\u207a<\/li>\n\n\n\n<li>Chlorine gains one electron \u2192 Cl\u207b<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Electrostatic attraction forms ionic bond.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Formula:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">NaCl<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q13. Oxygen Ion Formation<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Oxygen gains two electrons.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Ion Formed:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">O\u00b2\u207b<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Type:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Anion<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q14. Magnesium Chloride Formation<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Magnesium loses two electrons \u2192 Mg\u00b2\u207a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Each chlorine gains one electron \u2192 Cl\u207b<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">One Mg\u00b2\u207a combines with two Cl\u207b ions.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Formula:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">MgCl\u2082<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q15. Sodium Sulfide Formation<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Two sodium atoms donate one electron each.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Sulfur gains two electrons.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Formula:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Na\u2082S<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q16. Name the Following<\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Compound<\/th><th>Name<\/th><\/tr><\/thead><tbody><tr><td>CO\u2082<\/td><td>Carbon dioxide<\/td><\/tr><tr><td>NO\u2082<\/td><td>Nitrogen dioxide<\/td><\/tr><tr><td>SF\u2086<\/td><td>Sulfur hexafluoride<\/td><\/tr><tr><td>PCl\u2083<\/td><td>Phosphorus trichloride<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q17. Write Formulae<\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Compound<\/th><th>Formula<\/th><\/tr><\/thead><tbody><tr><td>Sodium hydrogencarbonate<\/td><td>NaHCO\u2083<\/td><\/tr><tr><td>Sulfur dioxide<\/td><td>SO\u2082<\/td><\/tr><tr><td>Ferric chloride<\/td><td>FeCl\u2083<\/td><\/tr><tr><td>Cuprous oxide<\/td><td>Cu\u2082O<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q18. Formula from Ions<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">(i) Fe\u00b3\u207a and OH\u207b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Formula:<br>Fe(OH)\u2083<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">(ii) K\u207a and CO\u2083\u00b2\u207b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Formula:<br>K\u2082CO\u2083<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q19. Electrical Conductivity Question<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Solution:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A compound conducting electricity only in solution is ionic.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Ionic bond is present.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q20. Molecular Mass of Nitric Acid<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Formula:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">HNO\u2083<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Calculation:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">= 1 + 14 + (16 \u00d7 3)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 63 u<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">63 u<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q21. Molecular Mass of Methane<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Formula:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">CH\u2084<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Calculation:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">= 12 + (1 \u00d7 4)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 16 u<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">16 u<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q22. Formula Unit Mass of KCl<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Calculation:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">= 39 + 35.5<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 74.5 u<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">74.5 u<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q23. Formula Unit Mass of Mg(OH)\u2082<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Calculation:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">= 24 + 2(16 + 1)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 24 + 34<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">= 58 u<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">58 u<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q24. Electronic Configuration Problem<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Given:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">11 protons, 12 neutrons, 10 electrons<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">(i) Atomic Number:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">11<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Mass Number:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">23<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">(ii) Nature:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Cation because protons &gt; electrons<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">(iii) Electronic Configuration:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">2, 8<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">(iv) Species:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Na\u207a<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Common Mistakes<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Confusing ionic and covalent bonds<\/li>\n\n\n\n<li>Writing wrong electronic configurations<\/li>\n\n\n\n<li>Forgetting brackets in polyatomic ions<\/li>\n\n\n\n<li>Ignoring charge balancing while writing formulae<\/li>\n\n\n\n<li>Incorrect molecular mass calculations<\/li>\n<\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">Exam Tips<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Learn valencies of common ions.<\/li>\n\n\n\n<li>Practice criss-cross method regularly.<\/li>\n\n\n\n<li>Remember definitions of cation and anion.<\/li>\n\n\n\n<li>Draw bonding diagrams neatly.<\/li>\n\n\n\n<li>Revise important laws carefully.<\/li>\n<\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">Practice MCQs<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">1. Which bond is formed by sharing electrons?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Ionic Bond<br>B. Covalent Bond<br>C. Metallic Bond<br>D. Hydrogen Bond<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">B. Covalent Bond<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">2. Which particle is positively charged?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Electron<br>B. Neutron<br>C. Proton<br>D. Atom<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">C. Proton<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">3. Formula of magnesium oxide:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Mg\u2082O<br>B. MgO\u2082<br>C. MgO<br>D. Mg\u2082O\u2082<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">C. MgO<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">4. Compound conducting electricity in aqueous solution is generally:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Covalent<br>B. Ionic<br>C. Organic<br>D. Neutral<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">B. Ionic<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">5. Molecular mass of water:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. 16 u<br>B. 17 u<br>C. 18 u<br>D. 20 u<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Answer:<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">C. 18 u<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">FAQ Section<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">Q1. What is a covalent bond?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A bond formed by sharing electrons between atoms.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q2. What is an ionic bond?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A bond formed due to transfer of electrons and electrostatic attraction between ions.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q3. Why do ionic compounds conduct electricity in water?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Because ions become free to move in solution.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q4. What is molecular mass?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Sum of atomic masses of all atoms in a molecule.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q5. What is formula unit mass?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Mass of simplest ratio of ions in an ionic compound.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Master Chemistry concepts with detailed notes, solved questions, MCQs, quizzes, and mock tests only on <a href=\"http:\/\/www.mymockmate.com\/\">www.mymockmate.com<\/a> and improve your exam performance today!<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n<div class=\"pdfprnt-buttons pdfprnt-buttons-post pdfprnt-top-bottom-right\"><a href=\"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/posts\/2521?print=print\" class=\"pdfprnt-button pdfprnt-button-print\" target=\"_blank\" ><img decoding=\"async\" src=\"https:\/\/mymockmate.com\/notes\/wp-content\/plugins\/pdf-print\/images\/print.png\" alt=\"image_print\" title=\"Print Content\" \/><span class=\"pdfprnt-button-title pdfprnt-button-print-title\">Print<\/span><\/a> <span class=\"pdfprnt-count-generation\"><\/span><\/div>\n    <div class=\"xs_social_share_widget xs_share_url after_content \t\tmain_content  wslu-style-1 wslu-share-box-shaped wslu-fill-colored wslu-none wslu-share-horizontal wslu-theme-font-no wslu-main_content\">\n\n\t\t\n        <ul>\n\t\t\t        <\/ul>\n    <\/div> \n","protected":false},"excerpt":{"rendered":"<p> Short Intro This chapter introduces the atomic nature of matter and explains how atoms combine to form<\/p>\n","protected":false},"author":3,"featured_media":2524,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_surecart_dashboard_logo_width":"180px","_surecart_dashboard_show_logo":true,"_surecart_dashboard_navigation_orders":true,"_surecart_dashboard_navigation_invoices":true,"_surecart_dashboard_navigation_subscriptions":true,"_surecart_dashboard_navigation_downloads":true,"_surecart_dashboard_navigation_billing":true,"_surecart_dashboard_navigation_account":true,"postBodyCss":"","postBodyMargin":[],"postBodyPadding":[],"postBodyBackground":{"backgroundType":"classic","gradient":""},"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[22,4,12],"tags":[1380,1381,1382,1385,1383,1386,1384,1387],"class_list":["post-2521","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cbse","category-class-9","category-science","tag-atomic-foundations-of-matter","tag-chemical-bonding","tag-covalent-bond","tag-dalton-atomic-theory","tag-ionic-bond","tag-law-of-conservation-of-mass","tag-law-of-constant-proportions","tag-molecular-mass"],"jetpack_publicize_connections":[],"_links":{"self":[{"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/posts\/2521","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/comments?post=2521"}],"version-history":[{"count":2,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/posts\/2521\/revisions"}],"predecessor-version":[{"id":2649,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/posts\/2521\/revisions\/2649"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/media\/2524"}],"wp:attachment":[{"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/media?parent=2521"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/categories?post=2521"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mymockmate.com\/notes\/wp-json\/wp\/v2\/tags?post=2521"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}