2025 Chemistry Final Medium Exam

A neutral atom of sulfur has an atomic number of 16 and a mass number of 32. How many protons, neutrons, and electrons does it contain?

• 16 protons, 16 neutrons, 16 electrons
• 16 protons, 15 neutrons, 16 electrons
• 16 protons, 16 neutrons, 15 electrons
• 32 protons, 16 neutrons, 16 electrons
• 16 protons, 32 neutrons, 16 electrons

A neutral magnesium atom loses two electrons. What is the resulting ion’s charge and electron configuration?

• 2+, 1s² 2s² 2p⁶
• 2−, 1s² 2s² 2p⁶ 3s²
• 2+, 1s² 2s² 2p⁶ 3s²
• 0, 1s² 2s² 2p⁶ 3s²
• 1+, 1s² 2s² 2p⁶ 3s¹

Which group on the periodic table contains elements that are most reactive with water?

• Group 1 - Alkali metals
• Group 2 - Alkaline earth metals
• Group 17 - Halogens
• Group 18 - Noble gases
• Group 14 - Carbon family

Which statement best explains why alkali metals are more reactive than alkaline earth metals?

• They have lower atomic mass
• They only need to lose 1 electron to stabilize
• They form stronger ionic bonds
• They are more electronegative
• They are smaller atoms

Which atom has a stronger attraction for electrons in a bond: sulfur or chlorine? Explain using periodic trends.

• Sulfur, due to size
• Sulfur, due to higher mass
• Chlorine, due to higher electronegativity
• Chlorine, due to fewer protons
• They are equal

Predict the product and name of the compound formed between calcium and fluorine.

• CaF₂, calcium fluoride
• Ca₂F, dicalcium fluoride
• CaF, monocalcium fluoride
• Ca₂F₂, calcium difluoride
• CaF₂, fluorine calcium

An atom of iron has 26 protons and 30 neutrons. What is the mass number, and what type of atom is it?

• 56, neutral atom
• 56, isotope
• 26, ion
• 30, cation
• 26, isotope

What trend is observed across a period from left to right on the periodic table?

• Atomic radius increases
• Ionization energy decreases
• Electronegativity decreases
• Atomic number decreases
• Electronegativity increases

Which of the following has the same number of valence electrons as oxygen?

• Nitrogen
• Sulfur
• Carbon
• Fluorine
• Helium

How do you determine the limiting reactant in a reaction using mole ratios?

• Convert all reactants to mass
• Compare actual mole values to coefficients
• Use molar mass directly
• Choose the reactant with the largest mass
• Balance the equation only