ATOM AND MOLECULE CLASS 9 :Atoms are the fundamental building blocks of matter, forming the basis of everything around us. In Class 9, students explore the characteristics of atoms, including their structure and types. Each atom consists of protons, neutrons, and electrons, which contribute to its properties and behaviors.
ATOM AND MOLECULES QUIZ HERE
ATOM AND MOLECULE CLASS 9: A GREAT STUDY Atoms are the fundamental building blocks of matter. Understanding them is crucial for Class 9 students, as they form the basis for countless scientific principles. An atom consists of protons, neutrons, and electrons, each playing a vital role in its behavior.
The Basics of Molecules: ATOM AND MOLECULE CLASS 9
Molecules are formed when two or more atoms bond together. This section of the syllabus highlights the importance of molecular structure and how different combinations produce various substances. Mastering molecules allows students to grasp chemical reactions more comprehensively.
Why Study Atoms and Molecules?
Studying atoms and molecules in Class 9 is essential for building a solid foundation in chemistry. It helps students understand the composition of matter, leading to a greater appreciation of the world around us. With this knowledge, students can excel in their future science courses.
| 1 | According to Avogadro’s law, equal volumes of all gases at the same temperature and pressure contain the same… |
number of atoms | number of molecules | mass | density | | avogadro, gas law, laboratory | equal volumes, gas molecules, illustration |
| 2 | The atomic number of an element is defined as the number of…
| neutrons | protons | protons + neutrons | electrons + neutrons | B | periodic table, atomic number, chemistry | protons, nucleus, subatomic |
| 3 | Which of the following pairs are isotopes of the same element?
| ¹H₁ and ²He₄ | ¹⁴C and ¹²C | ¹⁶O and ¹⁶N | ²³Na and ²⁴Mg | B | isotope notation, nuclide symbols, blackboard | carbon isotopes, mass number, comparison |
| 4 | The molar mass of calcium nitrate, Ca(NO₃)₂, is approximately…
| 102.09 g mol⁻¹ | 164.10 g mol⁻¹ | 178.25 g mol⁻¹ | 80.04 g mol⁻¹ | B | chemical formula, molar mass, calculator | periodic table, Ca(NO3)2, molar mass |
| 5 | Which of the following is a tri-atomic molecule?
| O₂ | CO₂ | N₂ | He | B | molecular models, triatomic, carbon dioxide | CO2 molecule, three atoms, ball-stick |
| 6 | The mass percentage of nitrogen in ammonia (NH₃) is closest to…
| 17.65 % | 75 % | 82.35 % | 18.65 % | C | ammonia flask, percentage composition, chemistry | nitrogen percent, NH3, pie chart |
| 7 | A compound contains 40 % sulfur and 60 % oxygen by mass. Its empirical formula is…
| SO | SO₂ | SO₃ | S₂O₃ | C | empirical formula, sulfur oxygen, scales | SO3 structure, sulfur trioxide, formula |
| 8 | Which statement correctly describes a molecule?
| Smallest particle of an element that takes part in a reaction | Positively charged atom | Group of two or more atoms held together by chemical bonds | Substance made of only one kind of atom | C | molecule concept, atoms bonding, textbook | molecular bonding, group of atoms, diagram |
| 9 | How many moles of CO₂ are present in 44 g of CO₂?
| 0.5 mol | 1 mol | 2 mol | 3 mol | B | weigh scale, CO2 gas cylinder, mole concept | 1 mole, Avogadro constant, CO2 illustration |
| 10 | Which of the following scientific laws led to the concept of molecules?
| Law of conservation of mass | Law of definite proportions | Avogadro’s law | Boyle’s law | C | history of chemistry, law comparison, scroll | Avogadro portrait, molecule concept, gas law |
| 11 | The number of electrons present in an O²⁻ ion is…
| 6 | 8 | 10 | 12 | C | oxygen ion, electron cloud, charge symbol | 10 electrons, oxide ion, subatomic particles |
| 12 | The fixed mass ratio of hydrogen to oxygen (1 : 8) in water illustrates the…
| Law of multiple proportions | Law of definite proportions | Gay-Lussac’s law | Dalton’s law of partial pressures | B | water composition, law diagram, beaker | definite proportion, H2O ratio, chemistry law |
| 13 | Which of the following species is an example of a molecular ion?
| Na⁺ | OH⁻ | Cl⁻ | Ne | B | ions in solution, molecular ion, test tube | hydroxide ion, OH-, polyatomic, model |
| 14 | How many atoms are present in one formula unit of aluminium sulfate, Al₂(SO₄)₃?
| 15 | 17 | 18 | 20 | B | aluminium sulfate, formula breakdown, chalkboard | 17 atoms, atom count, structural formula |
| 15 | Atoms of the same element that have different numbers of neutrons are called…
| isotopes | isobars | isotones | isoelectronic species | A | neutron difference, atomic nucleus, chart | isotope examples, same Z different A, illustration |
| 16 | The empirical formula of glucose (C₆H₁₂O₆) is…
| CHO | CH₂O | C₂H₄O₂ | C₃H₆O₃ | B | glucose molecule, empirical vs molecular, hexagon | CH2O unit, simplified formula, diagram |
| 17 | Which of the following halogens has the largest atomic radius?
| F | Cl | Br | I | D | halogen group, atomic radius trend, periodic table | iodine atom, atomic size, trend arrow |
| 18 | The ionic charges present in aluminium oxide are…
| Al²⁺ and O²⁻ | Al³⁺ and O²⁻ | Al⁺ and O²⁻ | Al³⁺ and O³⁻ | B | ionic compound lattice, aluminium oxide, crystal | Al3+ O2-, ionic charges, lattice model |
| 19 | The number of water molecules in 2 mol of H₂O is approximately…
| 6.022 × 10²³ | 1.204 × 10²⁴ | 1.806 × 10²⁴ | 3.011 × 10²³ | B | measuring moles, water molecules, Avogadro | 1.204e24, molecule count, large numbers | |
I20 | Which of the following has the same number of electrons as neon?
| Na⁺ | F⁻ | O²⁻ | All of the above | D | isoelectronic species, electron count, neon | Na+, F-, O2-, same electrons, comparison |
