Atoms and molecules.
1. What is the smallest unit of an element?
- A) Molecule
- B) Atom
- C) Compound
- D) Ion
2. Where are electrons located in an atom?
- A) Nucleus
- B) Electron cloud
- C) Proton shell
- D) Neutron shell
3. What is the charge of a sodium ion?
- A) Positive
- B) Negative
- C) Neutral
- D) Variable
4.Which of the following has the greatest mass?
- A) Proton
- B) Electron
- C) Neutron
- D) Both Proton and Neutron
5. Which subatomic particle determines the chemical behavior of an
atom?
- A) Neutron
- B) Proton
- C) Electron
- D) Nucleus
6. The periodic table is arranged by increasing:
- A) Mass
- B) Volume
- C) Atomic Number
- D) Density
7. Which of the following is a noble gas?
- A) Oxygen
- B) Nitrogen
- C) Argon
- D) Chlorine
8. Elements in the same group of the periodic table have:
- A) Similar properties
- B) Different properties
- C) Same atomic mass
- D) Different number of protons
9. What do you call elements that have similar properties and are in the
same column of the periodic table?
- A) Periods
- B) Groups
- C) Series
- D) Families
10. The most reactive group of metals is known as:
- A) Noble gases
- B) Alkali metals
- C) Transition metals
- D) Halogens
11. Which of the following is a characteristic of nonmetals?
- A) Good conductors of electricity
- B) Dull appearance
- C) Malleable
- D) High density
12. What is the atomic number of oxygen?
- A) 6
- B) 8
- C) 16
- D) 12
13. Which of the following elements is a metalloid?
- A) Aluminum
- B) Silicon
- C) Sodium
- D) Chlorine
14. What type of bond is formed when electrons are shared between
atoms?
- A) Ionic bond
- B) Covalent bond
- C) Metallic bond
- D) Hydrogen bond
15. Which of the following is an example of an ionic compound?
- A) H2O
- B) NaCl
- C) CO2
- D) CH4
16. How many valence electrons does sodium have?
- A) 1
- B) 2
- C) 3
- D) 4
17. A molecule of water (H2O) has:
- A) Two hydrogen atoms and one oxygen atom
- B) One hydrogen atom and two oxygen atoms
- C) Two oxygen atoms and one hydrogen atom
- D) Three hydrogen atoms and one oxygen atom
18. In a covalent bond, the atoms involved share:
- A) Electrons
- B) Protons
- C) Neutrons
- D) Nuclei
19. What type of bond exists in molecular oxygen (O2)?
- A) Single bond
- B) Double bond
- C) Triple bond
- D) Ionic bond
20. Which of the following compounds is covalent?
- A) NaCl
- B) HCl
- C) MgO
- D) KBr
21. The molecular formula of a compound shows:
- A) The number of atoms of each element
- B) The structure of the compound
- C) The physical state of the compound
- D) The color of the compound
22. The empirical formula for hydrogen peroxide (H2O2) is:
- A) H2O
- B) H2O2
- C) HO
- D) O2H2
23. The number of molecules in one mole of a substance is known as:
- A) Avogadro's number
- B) Molar mass
- C) Molecular weight
- D) Atomic mass
24. What is the empirical formula for C4H10?
- A) C2H5
- B) C4H10
- C) C1H2.5
- D) C4H8
25. The chemical formula for ammonium sulfate is:
- A) (NH4)2SO4
- B) NH4SO4
- C) (NH4)2S
- D) (NH4)2O
26. A compound that consists of only carbon and hydrogen is called:
- A) Hydrocarbon
- B) Hydroxide
- C) Halide
- D) Oxide
27. In a chemical reaction, the substances that undergo change are called:
- A) Products
- B) Reactants
- C) Catalysts
- D) Solvents
28. Which of the following is a sign of a chemical reaction?
- A) Change in color
- B) Formation of gas
- C) Change in temperature
- D) All of the above
29. The law of constant proportion of mass states that:
- A) Mass can be created
- B) ) elements present in a compound are always combined in
indefinite
Proportion.
- C) Mass is constant
- D) elements present in a compound are always combined in definite
Proportion.
30. In a balanced chemical equation, the number of atoms of each
element:
- A) Increases
- B) Decreases
- C) Stays the same
- D) Changes unpredictably
