The molar mass of CO2 is 44 g/mol. Therefore, 44 g of CO2 corresponds to 1 mole.

Molar mass of CO2 = 12 + 16*2 = 44 g/mol. Number of moles = mass/molar mass = 44g/44g/mol = 1 mole.

Moles = Molarity x Volume (L) = 2 moles/L x 0.5 L = 1 mole.

In NaClO3, the oxidation state of chlorine is +5. Sodium is +1 and each oxygen is -2, leading to the equation: +1 + x + 3(-2) = 0, solving gives x = +5.

In K2Cr2O7, the total charge from potassium (K) is +2, and oxygen (O) contributes -14. Let the oxidation state of Cr be x. The equation is 2x - 14 + 2 = 0, solving gives x = +6.

In NH4+, nitrogen has an oxidation state of -3. Each hydrogen is +1, leading to the equation: x + 4(+1) = +1, solving gives x = -3.

In H3PO4, phosphorus has an oxidation state of +5.

In H2SO4, the oxidation state of sulfur is +6. Each hydrogen is +1 and each oxygen is -2, leading to the equation: 2(+1) + x + 4(-2) = 0, solving gives x = +6.

In H2SO4, the oxidation state of sulfur is +6.

The general solution is y = Ce^(4x). Using the initial condition y(0) = 2, we find C = 2, thus y = 2e^(4x).

Percentage by mass = (mass of solute / total mass) × 100 = (15 g / (15 g + 85 g)) × 100 = 17.65%.

Percentage concentration = (mass of solute / mass of solution) × 100 = (15 g / 150 g) × 100 = 10%

Percentage concentration = (mass of solute / mass of solution) × 100 = (20 g / 200 g) × 100 = 10%.

Argon is located in Period 3 of the periodic table.

Lithium is located in period 2 of the periodic table.

Lithium is located in period 2 of the periodic table.

Sodium is in period 3 of the periodic table.

Using the formula for weak acids, pH = 0.5(pKa - logC) = 0.5(4.74 - log(0.001)) = 3.87.

pH = -log(0.001) = 3.

For a strong acid like HCl, pH = -log[H+] = -log(0.01) = 2.

Na2CO3 is a basic salt, pH is approximately 11.5.

pOH = -log(0.01) = 2; pH = 14 - pOH = 14 - 2 = 12.

H3PO4 is a triprotic acid; for a dilute solution, the first dissociation dominates, giving pH ≈ 2.

Using the formula for weak acids, pH = 0.5(pKa - log[C]) where pKa = -log(1.8 x 10^-5) ≈ 4.74. pH = 0.5(4.74 - log(0.05)) ≈ 4.7.

NaCl is a neutral salt, so the pH remains 7.

NH4Cl is a salt of a weak base and strong acid, pH < 7. Calculate using hydrolysis: pH ≈ 4.75.

K2CO3 is a salt of a weak acid (H2CO3) and strong base (KOH), resulting in a basic solution with pH around 10.

K2SO4 is a neutral salt formed from a strong acid (H2SO4) and a strong base (KOH). Therefore, the pH of the solution is 7.

NH4Cl is an acidic salt, pH is approximately 5.1.

Using the formula for salt of weak acid, pH = 14 + 0.5(pKa + logC) = 14 + 0.5(4.74 + log(0.1)) = 9.25.