Atoms and Molecules (परमाणु एवं अणु) Ch(3) Practice Quiz in Hindi Part – 2 || Class 9 Science Practice Quizzes in English Posted on February 28, 2025February 28, 2025 by Anshul Gupta0% 0 votes, 0 avg 0 Atoms and Molecules (परमाणु एवं अणु) Ch(3)Practice Quiz in Hindi Part – 2 || Class 9 Science Practice Quizzes in English 1 / 201. What is the formula unit mass of a substance? A. The number of formula units in a compound. B. The valency of the compound. C. The mass of a single formula unit of the compound. D. The sum of the atomic masses of all atoms in a formula unit of a compound. Explanation: The formula unit mass is the total mass of a formula unit, which is the smallest unit of an ionic compound. 2 / 202. What is the molar mass of ethyne (C2H2)? A. 28 g/mol B. 26 g/mol C. 30 g/mol D. 32 g/mol Explanation: The molar mass of ethyne is calculated as: 2 (atomic mass of carbon) + 2 (atomic mass of hydrogen) = 2 (12 g/mol) + 2 (1 g/mol) = 26 g/mol.3 / 203. What is the valency of oxygen? A. 2 B. 4 C. 3 D. 1 Explanation: The valency of oxygen is 2, meaning it can form two chemical bonds with other elements. 4 / 204. What is the chemical formula for sodium carbonate? A. Na(CO3)2 B. Na2(CO3)2 C. Na2CO3 D. NaCO3 Explanation: The chemical formula for sodium carbonate is Na2?CO3?, as sodium has a valency of 1 and the carbonate group (CO3) has a valency of 2. 5 / 205. What is the combining power of an element called? A. Valency B. Atomic mass C. Ionization energy D. Atomicity Explanation: Valency is the combining power of an element, which determines how its atoms will combine with atoms of other elements to form compounds. 6 / 206. What is the chemical formula for ammonium sulphate? A. NH4SO4 B. (NH4)2SO4 C. (NH4)2(SO4)2 D. NH4(SO4)2 Explanation: The chemical formula for ammonium sulphate is (NH4?)2?SO4?, as the ammonium group (NH4) has a valency of 1 and the sulphate group (SO4) has a valency of 2. 7 / 207. What is the chemical formula for baking powder? A. CaCO3 B. NaHCO3 C. NaCl D. NaOH Explanation: Baking powder is chemically known as sodium bicarbonate or sodium hydrogen carbonate, with the formula NaHCO3?. 8 / 208. What is the chemical formula for calcium hydroxide? A. CaOH2 B. Ca(OH)2 C. CaOH D. Ca2(OH) Explanation: The chemical formula for calcium hydroxide is Ca(OH)2?, as calcium has a valency of 2 and the hydroxyl group (OH) has a valency of 1. 9 / 209. What is the chemical formula for quicklime? A. CaO B. CaCl2 C. Ca(OH)2 D. CaCO3 Explanation: Quicklime is the common name for calcium oxide, which has the chemical formula CaO.10 / 2010. What is the molar mass of nitric acid (HNO3)? A. 63 g/mol B. 65 g/mol C. 69 g/mol D. 67 g/mol Explanation: The molar mass of nitric acid is calculated as: 1 (atomic mass of hydrogen) + 1 (atomic mass of nitrogen) + 3 (atomic mass of oxygen) = 1 (1 g/mol) + 1 (14 g/mol) + 3 (16 g/mol) = 63 g/mol.11 / 2011. What is the formula unit mass of calcium chloride (CaCl2)? A. 111 u B. 75.5 u C. 71 u D. 142 u Explanation: The formula unit mass of calcium chloride is calculated as: 1 (atomic mass of calcium) + 2 (atomic mass of chlorine) = 1 (40 u) + 2 (35.5 u) = 111 u. 12 / 2012. What is the chemical formula for magnesium chloride? A. MgCl B. Mg2Cl C. MgCl2 D. Mg2Cl2 Explanation: The chemical formula for magnesium chloride is MgCl2?, as magnesium has a valency of 2 and chlorine has a valency of 1. 13 / 2013. What is the molecular mass of water (H2O)? A. 16 u B. 18 u C. 10 u D. 20 u Explanation: The molecular mass of water is calculated as: 2 (atomic mass of hydrogen) + 1 (atomic mass of oxygen) = 2 (1 u) + 1 (16 u) = 18 u. 14 / 2014. What is the molar mass of the phosphorus molecule (P4)? A. 124 g/mol B. 248 g/mol C. 62 g/mol D. 31 g/mol Explanation: The molar mass of the phosphorus molecule is calculated as: 4 (atomic mass of phosphorus) = 4 (31 g/mol) = 124 g/mol.15 / 2015. What is the chemical formula for aluminium oxide? A. Al2O B. AlO C. AlO3 D. Al2O3 Explanation: The chemical formula for aluminium oxide is Al2?O3?, as aluminium has a valency of 3 and oxygen has a valency of 2. 16 / 2016. What is the molar mass of the sulfur molecule (S8)? A. 128 g/mol B. 32 g/mol C. 64 g/mol D. 256 g/mol Explanation: The molar mass of the sulfur molecule is calculated as: 8 (atomic mass of sulfur) = 8 (32 g/mol) = 256 g/mol.17 / 2017. What is the molecular mass of a substance? A. The sum of the atomic masses of all the atoms in a molecule of the substance. B. The mass of a single atom of the substance. C. The valency of the substance. D. The number of atoms in a molecule of the substance. Explanation: The molecular mass is the total mass of a molecule, calculated by adding the atomic masses of all the atoms in its chemical formula. 18 / 2018. What is the molar mass of hydrochloric acid (HCl)? A. 37.5 g/mol B. 36.5 g/mol C. 35.5 g/mol D. 38.5 g/mol Explanation: The molar mass of hydrochloric acid is calculated as: 1 (atomic mass of hydrogen) + 1 (atomic mass of chlorine) = 1 (1 g/mol) + 1 (35.5 g/mol) = 36.5 g/mol.19 / 2019. Which of the following is NOT a polyatomic ion? A. Chloride (Cl−) B. Ammonium (NH4+) C. Hydroxide (OH−) D. Nitrate (NO3−) Explanation: Chloride is a monatomic ion, consisting of a single chlorine atom with a negative charge. 20 / 2020. What is the chemical formula for sodium chloride? A. NaCl2 B. NaCl C. Na2Cl D. Na2Cl2 Explanation: The chemical formula for sodium chloride, commonly known as table salt, is NaCl. Please insert your information to see your ranking अपनी Ranking जानने के लिए कृपया अपनी जानकारी भरे NamePhone Number Your score isThe average score is 0% 0% Restart quiz Category: Class 9 Science Quizzes in English
