CHEM 101 Final Ivy Tech| 200 Questions| With Complete Solutions

CHEM 101 Final Ivy Tech| 200 Questions|
With Complete Solutions
 Course
 CHEM 101
1. Which of the following is the correct electron configuration for the element with atomic
number 12 (Magnesium, Mg)?

A) [Ne] 3s²
B) [Ne] 2s² 2p⁶ 3s²
C) [Ar] 4s²
D) 1s² 2s² 2p⁶ 3s² 3p⁶

✅ Correct Answer: A) [Ne] 3s²

Solution:
Magnesium (Mg) has an atomic number of 12. The electron configuration starts with the
nearest noble gas, Neon (Ne), which has an electron configuration of [Ne] = 1s² 2s² 2p⁶. After
Neon, the next two electrons go into the 3s orbital, resulting in [Ne] 3s².



2. What is the molar mass of calcium chloride (CaCl₂)?

A) 97.0 g/mol
B) 146.0 g/mol
C) 110.0 g/mol
D) 147.0 g/mol

✅ Correct Answer: B) 146.0 g/mol

Solution:
To find the molar mass of CaCl₂, we sum the atomic masses of each element:

 Ca = 40.08 g/mol

 Cl = 35.45 g/mol × 2 (because there are two chlorine atoms)

Molar mass of CaCl₂ = 40.08 + (2 × 35.45) = 146.0 g/mol



3. Which of the following is the correct molecular formula for a compound that contains 1.50
moles of sulfur and 6.00 moles of oxygen?

,A) SO₃
B) SO₂
C) S₂O₃
D) S₃O₆

✅ Correct Answer: A) SO₃

Solution:
The ratio of sulfur to oxygen is 1.50:6.00, which simplifies to 1:4. Therefore, the molecular
formula is SO₃, which represents sulfur trioxide.



4. What is the oxidation state of sulfur in H₂SO₄ (sulfuric acid)?

A) +4
B) +6
C) -2
D) 0

✅ Correct Answer: B) +6

Solution:
In H₂SO₄, hydrogen has an oxidation state of +1 and oxygen has an oxidation state of -2. The
sum of the oxidation states must equal zero because the molecule is neutral.
Let the oxidation state of sulfur be x.

For H₂SO₄:
2(+1) + x + 4(-2) = 0
2+x-8=0
x = +6

Thus, the oxidation state of sulfur is +6.



5. What is the pH of a solution with a hydrogen ion concentration of 1 × 10⁻⁴ M?

A) 4
B) 3
C) 5
D) 6

✅ Correct Answer: A) 4

,Solution:
The pH is calculated using the formula:
pH = -log[H⁺]

For [H⁺] = 1 × 10⁻⁴ M:
pH = -log(1 × 10⁻⁴) = 4



6. What is the empirical formula of a compound that contains 4.0 grams of carbon, 0.8 grams
of hydrogen, and 3.2 grams of oxygen?

A) CH₂O
B) C₄H₈O₄
C) C₃H₈O₄
D) CH₄O₂

✅ Correct Answer: A) CH₂O

Solution:
Step 1: Find the moles of each element:

 Moles of C = 4.0 g ÷ 12.01 g/mol = 0.333 mol

 Moles of H = 0.8 g ÷ 1.008 g/mol = 0.794 mol

 Moles of O = 3.2 g ÷ 16.00 g/mol = 0.200 mol

Step 2: Divide each mole value by the smallest number of moles (0.200 mol in this case):

 C: 0.333 ÷ 0.200 = 1.67

 H: 0.794 ÷ 0.200 = 3.97 ≈ 4

 O: 0.200 ÷ 0.200 = 1

Step 3: Round to the nearest whole numbers to get the empirical formula: CH₂O.



7. A reaction is classified as exothermic. Which of the following is true about the reaction?

A) Energy is absorbed from the surroundings
B) The products have higher energy than the reactants
C) Heat is released into the surroundings
D) The enthalpy change (ΔH) is positive

✅ Correct Answer: C) Heat is released into the surroundings

, Solution:
In exothermic reactions, energy is released to the surroundings. This results in the products
having lower energy than the reactants, and the enthalpy change (ΔH) is negative.



8. Which of the following compounds is most likely to be soluble in water?

A) NaCl
B) BaSO₄
C) AgCl
D) PbS

✅ Correct Answer: A) NaCl

Solution:
NaCl is an ionic compound, and ionic compounds are generally soluble in water due to their
ability to dissociate into ions. BaSO₄, AgCl, and PbS are insoluble in water based on solubility
rules.



9. A gas occupies a volume of 4.0 L at 300 K and 1.0 atm. What will be the new volume if the
temperature is increased to 600 K while the pressure remains constant?

A) 2.0 L
B) 4.0 L
C) 6.0 L
D) 8.0 L

✅ Correct Answer: C) 6.0 L

Solution:
Using Charles' Law (V₁/T₁ = V₂/T₂), where V is volume and T is temperature (in Kelvin):
V₁ = 4.0 L, T₁ = 300 K, T₂ = 600 K

V₂ = (V₁ × T₂) / T₁
V₂ = (4.0 L × 600 K) / 300 K = 8.0 L



10. How many moles are present in 25.0 grams of sodium chloride (NaCl)?

A) 0.25 mol
B) 0.43 mol