Q1. What is the atomic mass for potassium?

Background

Topic: Atomic Structure and Periodic Table

This question tests your knowledge of the periodic table, specifically the atomic mass of elements.

Key Terms:

• Atomic mass: The weighted average mass of the atoms in a naturally occurring element, usually found below the element symbol on the periodic table.

Step-by-Step Guidance

1. Locate potassium (K) on the periodic table.

2. Identify the number listed as the atomic mass (not the atomic number).

3. Remember that atomic mass is usually a decimal number, while atomic number is a whole number.

Try solving on your own before revealing the answer!

Q2. Which of the following is an ionic compound?

Background

Topic: Chemical Bonding

This question tests your ability to distinguish between ionic and covalent compounds.

Key Terms:

• Ionic compound: Formed between metals and nonmetals, involving the transfer of electrons.

• Covalent compound: Formed between nonmetals, involving the sharing of electrons.

Step-by-Step Guidance

1. Identify which elements in each compound are metals and which are nonmetals.

2. Recall that ionic compounds are typically formed between a metal and a nonmetal.

3. Look for a compound in the list that fits this pattern.

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Q3. Without using a calculator, solve the following problem:

Background

Topic: Scientific Notation and Exponents

This question tests your ability to manipulate numbers in scientific notation and apply exponent rules.

Key Terms and Formulas:

• Scientific notation: Expressing numbers as .

• Exponent rules: and .

Step-by-Step Guidance

1. Multiply the two numbers in the numerator: .

2. Apply the exponent rule for multiplication: .

3. Square the result: .

4. Divide by : .

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Q4. Identify the common substance that has the lowest density.

Background

Topic: Density and Properties of Matter

This question tests your understanding of the concept of density and the relative densities of common substances.

Key Terms:

• Density:

Step-by-Step Guidance

1. Recall the typical densities of the substances listed (sugar, ethanol, table salt, aluminum, titanium).

2. Remember that metals generally have higher densities than nonmetals and liquids.

3. Compare the densities to determine which is the lowest.

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Q5. Which of the following contains the fewest atoms? (10.0 g of Kr, Li, Ar, Na, or Cs)

Background

Topic: Moles, Atoms, and Molar Mass

This question tests your ability to relate mass, molar mass, and number of atoms.

Key Terms and Formulas:

• Molar mass: The mass of one mole of a substance (g/mol).

• Number of moles:

• Number of atoms:

Step-by-Step Guidance

1. Find the molar mass of each element listed.

2. Calculate the number of moles in 10.0 g for each element using .

3. The element with the highest molar mass will have the fewest moles, and thus the fewest atoms for the same mass.

Try solving on your own before revealing the answer!