Question 1
Multiple ChoiceWhich element does the chemical symbol "O" represent?
Explanation
The symbol "O" stands for oxygen, the element essential for respiration and combustion.
Question 2
Multiple ChoiceWhat is the chemical symbol for sodium?
Explanation
Sodium's symbol is "Na," derived from its Latin name natrium.
Question 3
Multiple ChoiceWhich subatomic particle carries a positive electric charge?
Explanation
Protons carry a positive charge, neutrons are neutral, and electrons carry a negative charge.
Question 4
Multiple ChoiceThe atomic number of an element is equal to the number of what in one of its atoms?
Explanation
The atomic number equals the number of protons in the nucleus, which defines the element's identity.
Question 5
Multiple ChoiceWhat is the chemical formula for water?
Explanation
Water is H2O — two hydrogen atoms bonded to one oxygen atom.
Question 6
Multiple ChoiceA solution with a pH of 3 is best described as which of the following?
Explanation
A pH below 7 is acidic, a pH of 7 is neutral, and a pH above 7 is basic. A pH of 3 is therefore acidic.
Question 7
Multiple ChoiceWhich best describes a chemical compound?
Explanation
A compound is a pure substance made of two or more different elements chemically bonded together in a fixed ratio, such as water (H2O) or table salt (NaCl).
Question 8
True FalseIn an ionic bond, one atom transfers one or more electrons to another atom, producing oppositely charged ions that attract each other.
Explanation
Ionic bonds form by the transfer of electrons, creating positive and negative ions that attract. Covalent bonds, by contrast, form when atoms share electrons.
Question 9
True FalseThe periodic table arranges the elements in order of increasing atomic number.
Explanation
Modern periodic tables are ordered by increasing atomic number (number of protons), with elements in the same column sharing similar chemical properties.
Question 10
Multiple SelectWhich of the following are noble gases? (Select all that apply.)
Explanation
Helium, neon, and argon are all noble gases in Group 18. Oxygen is not a noble gas — it is a reactive nonmetal in Group 16.