- 1. Atoms are the building blocks of matter, consisting of protons, neutrons, and electrons. Protons have a positive charge, neutrons are neutral, and electrons have a negative charge. When atoms bond together, they form molecules, which are combinations of two or more atoms held together by chemical bonds. Molecules can be simple, like water (H2O), or complex, like DNA. Understanding atoms and molecules is crucial in explaining the properties and behavior of all matter in the universe.
What is the smallest unit of an element that retains its properties?
A) Neutron
B) Atom
C) Molecule
D) Proton
- 2. What is the center of an atom where most of its mass is concentrated?
A) Electron Cloud
B) Shell
C) Nucleus
D) Orbit
- 3. Which subatomic particle has a positive charge?
A) Neutron
B) Photon
C) Proton
D) Electron
- 4. How many electrons can the first energy level of an atom hold?
A) 2 electrons
B) 4 electrons
C) 8 electrons
D) 6 electrons
- 5. In a covalent bond, atoms share which of the following?
A) Electrons
B) Nuclei
C) Neutrons
D) Protons
- 6. What is the atomic number of an element determined by?
A) Number of Protons
B) Atomic Mass
C) Number of Electrons
D) Number of Neutrons
- 7. What type of bond is formed when atoms transfer electrons?
A) Hydrogen bond
B) Covalent bond
C) Ionic bond
D) Metallic bond
- 8. The number of protons in an atom is equal to which of the following?
A) Isotopes
B) Atomic Mass
C) Mass Number
D) Atomic Number
- 9. What is the total number of electrons in a neutral atom?
A) Depends on the element
B) Equal to the number of protons
C) Double the number of protons
D) Half the number of protons
- 10. What is the sharing of a pair of electrons between atoms called?
A) Hydrogen Bond
B) Metallic Bond
C) Ionic Bond
D) Covalent Bond
- 11. How many electrons can the third energy level of an atom hold?
A) 8 electrons
B) 18 electrons
C) 2 electrons
D) 32 electrons
- 12. What is the term for an atom that has gained or lost electrons?
A) Molecule
B) Compound
C) Ion
D) Element
- 13. Atoms of the same element that have different numbers of neutrons are called what?
A) Elements
B) Ions
C) Isomers
D) Isotopes
- 14. Which of the following is a molecule composed of three oxygen atoms?
A) Water
B) Methane
C) Carbon Dioxide
D) Ozone
- 15. What is the chemical formula for water?
A) H2O
B) NaCl
C) CH4
D) CO2
- 16. Which element has the atomic number 1?
A) Carbon
B) Hydrogen
C) Nitrogen
D) Oxygen
- 17. What type of bond results from the attraction between oppositely charged ions?
A) Polar Bond
B) Ionic Bond
C) Covalent Bond
D) Metallic Bond
- 18. What is the scattering of light by colloidal particles called?
A) Tyndall Effect
B) Bohr Effect
C) Raman Effect
D) Compton Effect
- 19. What is the term for a group of atoms bonded together?
A) Element
B) Ion
C) Particle
D) Molecule
- 20. Which element has the atomic number 6?
A) Sodium
B) Carbon
C) Nitrogen
D) Oxygen
- 21. What is a molecule composed of only one type of atom?
A) Compound
B) Isotope
C) Element
D) Ion
- 22. What is the maximum number of electrons that can occupy the second energy level of an atom?
A) 4
B) 8
C) 6
D) 2
- 23. What is the charge of an ion that gains one electron?
A) Negative
B) Dual
C) Positive
D) Neutral
- 24. What is the chemical formula for table salt (sodium chloride)?
A) NaCl
B) CO2
C) NH3
D) H2O
- 25. Which subatomic particle has no charge?
A) Proton
B) Photon
C) Neutron
D) Electron
- 26. What happens to the mass number of an element when it gains a neutron?
A) Fluctuates
B) Increases
C) Remains unchanged
D) Decreases
- 27. H2SO4 is the chemical formula for?
A) Hydrochloric acid
B) Sulfuric acid
C) Nitric acid
D) Acetic acid
- 28. Which element has the symbol Fe in the periodic table?
A) Silver
B) Gold
C) Iron
D) Copper
- 29. Which subatomic particle has a negative charge?
A) Nucleus
B) Proton
C) Neutron
D) Electron
- 30. Molecules are formed by the combination of two or more what?
A) Neutrons
B) Atoms
C) Electrons
D) Protons
- 31. Which class of elements tend to lose electrons and form positive ions?
A) Nonmetals
B) Noble gases
C) Metalloids
D) Metals
- 32. What is the number of valence electrons in an atom of chlorine (Cl)?
A) 3
B) 7
C) 5
D) 9
- 33. What is the name for a positively charged ion?
A) Anion
B) Neutron
C) Isotope
D) Cation
- 34. What holds the protons and neutrons together in an atom's nucleus?
A) Gravity
B) Electric force
C) Strong nuclear force
D) Magnetic force
- 35. The outermost shell of an atom is known as the:
A) Nucleus
B) Proton shell
C) Electron cloud
D) Valence shell
- 36. Which of the following is a diatomic molecule?
A) O2
B) H2O
C) NaCl
D) CO2
- 37. What is the chemical formula for carbon dioxide?
A) CO3
B) CO
C) CO2
D) C2O
- 38. What is the study of the properties and behavior of atoms and molecules?
A) Physics
B) Geology
C) Chemistry
D) Biology
- 39. The Law of Conservation of Mass states that in a chemical reaction, mass is:
A) Created
B) Destroyed
C) Neither created nor destroyed
D) Lost as energy
- 40. How many electrons are in the valence shell of a nitrogen atom?
A) 5
B) 8
C) 1
D) 7
- 41. What is the SI unit for measuring the amount of a substance?
A) Gram
B) Coulomb
C) Mole
D) Liter
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