**Answer:**

Carbon dioxide (CO₂)

**Explanation:**

Carbonic acid decomposes to release water and carbon dioxide:

H₂CO₃ → H₂O + CO₂

In an aqueous solution, it has this two equilibriums where it release 2 protons. It is a weak acid:

H₂CO₃ + H₂O ⇄ HCO₃⁻ + H₃O⁺ Ka₁

HCO₃⁻ + H₂O ⇄ CO₃⁻² + H₃O⁺ Ka₂

**Answer:**

90.4 mL

**Explanation:**

**Step 1: Given data**

- Initial volume of the gas (V₁): 113 mL

- Initial pressure of the gas (P₁): 721 mmHg

- Final volume of the gas (V₂): ?

- Final pressure of the gas (P₂): 901 mmHg

**Step 2: Calculate the final volume of the gas**

According to Boyle's law, the volume of a gas is inversely proportional to the pressure. We can calculate the final volume of the gas using the following expression.

P₁ × V₁ = P₂ × V₂

V₂ = P₁ × V₁ / P₂

V₂ = 721 mmHg × 113 mL / 901 mmHg

V₂ = 90.4 mL

**Answer:**

25 mL

**Explanation:**

The reaction that takes place is:

- Ca(OH)₂ + 2HNO₃ → Ca(NO₃)₂ + 2H₂O

First we<u> calculate how many Ca(OH)₂ moles</u> were spent in the titration:

- 25.0 mL * 0.100 M = 2.5 mmol Ca(OH)₂

Then we <u>convert Ca(OH)₂ moles into HNO₃ moles</u>, using the <em>stoichiometric ratio</em>:

- 2.5 mmol Ca(OH)₂ * = 5.0 mmol HNO₃

Finally we <u>calculate the volume of required nitric acid solution</u>, using the <em>concentration</em>:

- 5.0 mmol ÷ 0.200 mmol/mL = 25 mL

**Answer:**

The volume is 59, 3 liters. See the explanation below, please

**Explanation:**

STP conditions (standard) correspond to 273K of temperature and 1 atm of pressure. These values are used and the volume is calculated, according to the formula:

PV = nRT

1 atm x V= 2, 65 moles x 0, 082 l atm/K mol x 272 K

V= 2, 65 moles x 0, 082 l atm/K mol x 272 K/1 atm = 59, 3 liters