Class 9 Practice Level 2 – Set 1 – Atoms and Molecules Leave a Comment / By anushka kumari / August 26, 2024 Class 9 Practice Level 2 - Set 1 – Atoms and Molecules Total questions: 25 1. What is the mass of one atom of carbon-12? Topic: Basic Concepts of Atoms and Molecules $ \displaystyle {1.66\text{ }\times \text{ }{{{10}}^{{-24}}}}$ g $ \displaystyle {2.00\text{ }\times \text{ }{{{10}}^{{-23}}}}$ g $ \displaystyle {1.99\text{ }\times \text{ }{{{10}}^{{-23}}}}$ g $ \displaystyle {1.99\text{ }\times \text{ }{{{10}}^{{-24}}}}$ g None 2. What is the relative atomic mass of an element? Topic: Basic Concepts of Atoms and Molecules The mass of an atom compared to 1/12th the mass of a carbon-12 atom The mass of an atom compared to 1/16th the mass of an oxygen-16 atom The mass of an atom compared to the mass of a hydrogen atom The mass of an atom compared to the mass of a helium atom None 3. What is the molecular mass of $ \displaystyle C{{O}_{2}}$? Topic: Basic Concepts of Atoms and Molecules 28 g/mol 32 g/mol 44 g/mol 40 g/mol None 4. According to the Law of Multiple Proportions, if two elements combine to form more than one compound, then the masses of one element that combine with a fixed mass of the other element are in the ratio of Topic: Laws of Chemical Combination Whole numbers Fractions Decimals None of the above None 5. Who discovered the Law of Definite Proportions? Topic: Laws of Chemical Combination John Dalton Joseph Proust Antoine Lavoisier Robert Boyle None 6. Which particle is not present in the nucleus of an atom? Topic: Atomic Structure Proton Neutron Electron All of the above None 7. What is the atomic number of an element with 11 protons and 12 neutrons? Topic: Atomic Structure 12 11 23 22 None 8. Which scientist proposed the plum pudding model of the atom? Topic: Atomic Structure Niels Bohr Ernest Rutherford J.J. Thomson James Chadwick None 9. What is the difference between the isotopes of an element? Topic: Isotopes Number of protons Number of neutrons Number of electrons Number of positrons None 10. Which isotope of hydrogen is used in nuclear fusion reactions? Topic: Isotopes Protium Deuterium Tritium None of the above None 11. What is the volume occupied by 1 mole of any gas at standard temperature and pressure (STP)? Topic: Mole Concept 22.4 L 24 L 22 L 23.5 L None 12. Calculate the number of moles in 88 grams of $ \displaystyle C{{O}_{2}}$? Topic: Mole Concept 1 mole 2 moles 3 moles 4 moles None 13. What is the molecular mass of nitrogen dioxide ($ \displaystyle N{{O}_{2}}$)? Topic: Molecular Mass and Mole Concept 38 g/mol 42 g/mol 46 g/mol 48 g/mol None 14. How many grams are there in 0.5 moles of sulphur dioxide ($ \displaystyle S{{O}_{2}}$)? Topic: Molecular Mass and Mole Concept 32 g 48 g 40 g 32.5 g None 15. What is the empirical formula of a compound with a molecular formula of $ \displaystyle {{{C}_{2}}{{H}_{4}}}$? Topic: Empirical and Molecular Formulas $ \displaystyle {{C}{H}}$ $ \displaystyle {C{{H}_{2}}}$ $ \displaystyle {{{C}_{2}}{{H}_{2}}}$ $ \displaystyle {C{{H}_{3}}}$ None 16. What is the molecular formula of a compound with an empirical formula of $ \displaystyle {C{{H}_{2}}}$ and a molar mass of 28 g/mol? Topic: Empirical and Molecular Formulas $ \displaystyle {{{C}_{2}}{{H}_{4}}}$ $ \displaystyle {C{{H}_{2}}}$ $ \displaystyle {{{C}_{3}}{{H}_{6}}}$ $ \displaystyle {{{C}_{4}}{{H}_{8}}}$ None 17. How many moles are present in 40 g of He? Topic: Chemical Reactions and Equations 10 moles 5 moles 20 moles 6 moles None 18. How many grams of water are produced when 2 moles of hydrogen react with 1 mole of oxygen? Topic: Chemical Reactions and Equations 18 g 36 g 54 g 72 g None 19. An element has an atomic number of 17 and a mass number of 35. How many neutrons does it have? Topic: Atomic Number and Mass Number 17 18 35 52 None 20. Which element has an atomic number of 13? Topic: Atomic Number and Mass Number Magnesium Silicon Aluminium Phosphorus None 21. Which element is represented by the symbol 'Fe'? Topic: Periodic Table and Elements Fluorine Iron Francium Fermium None 22. What is the atomic number of Neon? Topic: Periodic Table and Elements 8 10 12 14 None 23. In the reaction $ \displaystyle CaC{{O}_{3}}+\text{ }2HCl\text{ }\to \text{ }CaC{{l}_{2}}+\text{ }{{H}_{2}}O\text{ }+\text{ }C{{O}_{2}}$, how many moles of $ \displaystyle C{{O}_{2}}$ are produced from 1 mole of $ \displaystyle CaC{{O}_{3}}$? Topic: Stoichiometry 1 mole 2 moles 3 moles 4 moles None 24. How many moles of $ \displaystyle {{H}_{2}}O$ are produced when 2 moles of $\displaystyle C{{H}_{4}}$ react with 4 moles of $\displaystyle {{O}_{2}}$in the reaction $\displaystyle C{{H}_{4}}+\text{ }2{{O}_{2}}\to \text{ }C{{O}_{2}}+\text{ }2{{H}_{2}}O$ ? Topic: Stoichiometry 2 moles 3 moles 4 moles 5 moles None 25. What is the empirical formula of a compound with a molecular formula of $ \displaystyle {{C}_{6}}{{H}_{{12}}}{{O}_{6}}$ ? Topic: Empirical and Molecular Formulas $ \displaystyle {CHO}$ $ \displaystyle {{{C}_{2}}{{H}_{4}}{{O}_{2}}}$ $\displaystyle {C{{H}_{2}}O}$ $\displaystyle {{{C}_{3}}{{H}_{6}}{{O}_{3}}}$ None 1 out of 25 Time's up
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