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 typically 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. Check each option to see which one fits this pattern.

Try solving on your own before revealing the answer!

Q3. Without using a calculator, solve:

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 numbers inside the brackets: .

2. Apply the exponent rule for multiplication: .

3. Square the result: .

4. Apply the exponent rule for powers: .

5. Divide by using the exponent rule for division: .

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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 knowledge of the relative densities of common substances.

Key Terms:

• Density: Mass per unit volume, usually expressed as or .

Step-by-Step Guidance

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

2. Compare which is a solid metal, which is a liquid, and which are solids with lower densities.

3. Remember that ethanol is a liquid and generally less dense than solids like metals or salts.

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Q5. Which of the following contains the fewest atoms? (No calculation needed)

Background

Topic: Moles, Atomic Mass, and Counting Atoms

This question tests your understanding of the relationship between mass, molar mass, and number of atoms.

Key Terms:

• Molar mass: The mass of one mole of a substance, in grams per mole.

• Avogadro's number: atoms/mol.

Step-by-Step Guidance

1. Recall that for the same mass, the element with the highest molar mass will have the fewest moles, and thus the fewest atoms.

2. Compare the molar masses of Kr, Li, Ar, Na, and Cs.

3. Identify which element has the highest molar mass among the options.

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Q6. Identify the element that has an atomic number of 15.

Background

Topic: Periodic Table and Atomic Structure

This question tests your ability to use the periodic table to identify elements by atomic number.

Key Terms:

• Atomic number: The number of protons in the nucleus of an atom, unique to each element.

Step-by-Step Guidance

1. Locate atomic number 15 on the periodic table.

2. Match the atomic number to the correct element name.

3. Be careful not to confuse atomic number with atomic mass.

Try solving on your own before revealing the answer!