Q1. What is the atomic mass for potassium?

Background

Topic: Periodic Table & Atomic Mass

This question tests your knowledge of the periodic table and the concept of atomic mass, which is the weighted average mass of an element's isotopes.

Key Terms:

• Atomic mass: The average mass of atoms of an element, measured in atomic mass units (amu).

• Potassium: Chemical symbol K, an alkali metal.

Step-by-Step Guidance

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

2. Identify the atomic mass value listed for potassium.

3. Remember that atomic mass is usually a decimal number, not an integer.

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 based on their composition.

Key Terms:

• Ionic compound: Formed from a metal and a nonmetal, involving transfer of electrons.

• Covalent compound: Formed from two nonmetals, involving sharing of electrons.

Step-by-Step Guidance

1. Identify which compounds contain a metal and a nonmetal.

2. Recall that sodium (Na) is a metal and bromine (Br) is a nonmetal.

3. Compare the options to see which fits the definition of an ionic compound.

Try solving on your own before revealing the answer!

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

Background

Topic: Scientific Notation & Exponents

This question tests your ability to manipulate scientific notation and exponents without a calculator.

Key Terms & Formulas:

• Scientific notation: Expressing numbers as .

• Exponent rules: ;

Step-by-Step Guidance

1. Multiply and to get .

2. Square to get .

3. Divide by using exponent rules: .

Try solving on your own before revealing the answer!

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

Background

Topic: Density

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

Key Terms:

• Density:

• Substances: sugar, ethanol, table salt, aluminum, titanium

Step-by-Step Guidance

1. Recall the typical densities of the listed substances.

2. Compare solids (metals and salts) to liquids (ethanol).

3. Identify which substance is a liquid and generally has a lower density than solids.

Try solving on your own before revealing the answer!

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

Background

Topic: Moles & Atomic Mass

This question tests your understanding of how atomic mass affects the number of atoms in a given mass.

Key Terms & Formula:

• Atomic mass: Higher atomic mass means fewer atoms per gram.

• Number of atoms:

• = Avogadro's number ( atoms/mol)

Step-by-Step Guidance

1. Compare the atomic masses of Kr, Li, Ar, Na, and Cs.

2. Recognize that the element with the highest atomic mass will have the fewest atoms in 10.0 g.

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

Try solving on your own before revealing the answer!

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

Background

Topic: Periodic Table & Atomic Number

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

Key Terms:

• Atomic number: Number of protons in an atom.

• Element symbols: Si (silicon), O (oxygen), P (phosphorus), S (sulfur)

Step-by-Step Guidance

1. Locate atomic number 15 on the periodic table.

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

3. Recall the sequence of elements around atomic number 15.

Try solving on your own before revealing the answer!

Q7. Choose the homogeneous mixture from the list below.

Background

Topic: Mixtures

This question tests your understanding of the difference between homogeneous and heterogeneous mixtures.

Key Terms:

• Homogeneous mixture: Uniform composition throughout (e.g., solutions).

• Heterogeneous mixture: Non-uniform composition (e.g., mud, salsa).

Step-by-Step Guidance

1. Review the definitions of homogeneous and heterogeneous mixtures.

2. Analyze each option to determine if it is uniform throughout.

3. Identify which option is a solution or uniform mixture.

Try solving on your own before revealing the answer!

Q8. Cesium belongs to which group of the periodic table?

Background

Topic: Periodic Table Groups

This question tests your knowledge of periodic table group classifications.

Key Terms:

• Alkali metals: Group 1 elements.

• Halogens: Group 17 elements.

• Noble gases: Group 18 elements.

• Alkaline earth metals: Group 2 elements.

Step-by-Step Guidance

1. Locate cesium (Cs) on the periodic table.

2. Identify which group it belongs to based on its position.

3. Recall the properties of alkali metals.

Try solving on your own before revealing the answer!

Q9. Which one of the following compounds contains ionic bonds?

Background

Topic: Chemical Bonding

This question tests your ability to identify ionic compounds based on their constituent elements.

Key Terms:

• Ionic bond: Formed between a metal and a nonmetal.

• Covalent bond: Formed between two nonmetals.

Step-by-Step Guidance

1. Identify which compounds contain a metal and a nonmetal.

2. Recall that Sr (strontium) is a metal and O (oxygen) is a nonmetal.

3. Determine which compound fits the definition of an ionic bond.

Try solving on your own before revealing the answer!

Q10. Which of the following exists as a polyatomic molecule?

Background

Topic: Molecular Structure

This question tests your knowledge of elements that form polyatomic molecules (more than two atoms bonded together).

Key Terms:

• Polyatomic molecule: A molecule consisting of more than two atoms.

• Examples: (phosphorus), (sulfur)

Step-by-Step Guidance

1. Recall which elements naturally form polyatomic molecules.

2. Compare the options to see which forms molecules with more than two atoms.

3. Identify phosphorus as forming molecules.

Try solving on your own before revealing the answer!