MCQs On Stoichiometry And Stoichiometric Calculations

The limiting reactant is the reactant that is completely consumed in a chemical reaction, thereby limiting the amount of product that can be formed. It determines the maximum amount of product that can be obtained. In contrast, the reactant in excess is the reactant that is present in greater quantity than required for the reaction and is not completely consumed. The term "stoichiometry" refers to the quantitative relationship between reactants and products in a chemical reaction, while "stoichiometric amount" refers to the exact amount of reactants required for a reaction based on the stoichiometry.

One mole of any substance contains Avogadro's number of particles, which is approximately 6.023 x 10^23. In the case of H2O, one mole of water contains 6.023 x 10^23 water molecules. Therefore, the correct answer is 6.023 x 10^23.

The correct answer is "Number of molecules." One mole of any substance contains Avogadro's number of particles, which is approximately 6.022 x 10^23. Therefore, both one mole of ethanol and one mole of ethane would have the same number of molecules, which is equal to Avogadro's number.

N2H4 contains the highest percentage by mass of nitrogen because it has two nitrogen atoms in its formula, compared to only one nitrogen atom in the other compounds. Since the percentage by mass is calculated by dividing the mass of nitrogen in the compound by the total mass of the compound and multiplying by 100, having two nitrogen atoms in N2H4 increases the numerator and thus the percentage of nitrogen in the compound.

When methane reacts with steam, it produces hydrogen gas (H2) and carbon monoxide (CO). The question asks for the volume of hydrogen gas that can be obtained from 100 cm3 of methane at standard temperature and pressure. Since the reaction is stoichiometric, it means that for every molecule of methane, one molecule of hydrogen gas is produced. Therefore, the volume of hydrogen gas obtained will be equal to the volume of methane used, which is 100 cm3.

The given question states that a flask contains 500 cm3 of SO2 at STP. To determine the mass of the SO2 in the flask, we need to use the ideal gas law equation, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. At STP, the pressure is 1 atm and the temperature is 273 K. We can rearrange the equation to solve for n, the number of moles. The molar mass of SO2 is 64 g/mol. By substituting the given values into the equation, we can calculate that n is approximately 0.0223 mol. Finally, we can calculate the mass of SO2 by multiplying the number of moles by the molar mass, which gives us approximately 1.427 g.

Avogadro's constant (6.022 × 10^23 mol^-1) represents the number of particles, specifically molecules or atoms, in one mole of a substance. This constant allows chemists to relate the mass of a substance to the number of particles it contains. Option A is incorrect because it refers to the number of atoms in 12 grams of carbon-12, which is technically Avogadro's number (6.022 × 10²³ atoms/mol), but it represents a specific isotope of carbon. Option C is incorrect because it refers to the number of electrons in 1 gram of hydrogen, which is unrelated to Avogadro's constant. Option D is incorrect because it mentions protons, whereas Avogadro's constant is associated with the number of molecules or atoms, not protons. 

The molar mass of Al2O3 is 102 g/mol. To find the mass of aluminum in 204 g of Al2O3, we need to calculate the mass of one mole of Al2O3 and then divide it by the molar mass of aluminum. Since there are 2 moles of aluminum in one mole of Al2O3, the mass of aluminum is 2 times the molar mass of aluminum. Therefore, the mass of aluminum in 204 g of Al2O3 is 2 * (26.98 g/mol) = 108 g.

When four moles of SO2 are oxidized to SO3, the balanced chemical equation shows that two moles of SO2 react with one mole of O2 to produce two moles of SO3. Therefore, to oxidize four moles of SO2, we would need two moles of O2.

To find the mass of 2 moles of chlorine gas (Cl₂), use the following steps:

Calculate the molar mass of Cl₂:

Chlorine gas (Cl₂) consists of two chlorine atoms.

Molar mass of Cl₂ = 2 × 35.5 g/mol = 71 g/mol.

Calculate the mass of 2 moles of Cl₂:

Mass = number of moles × molar mass

Mass = 2 moles × 71 g/mol = 142 grams.

The answer, 3.01 x 10^23, is the correct option because it represents Avogadro's number, which is the number of atoms or molecules in one mole of a substance. In this case, since the necklace contains 6g of diamond, which has a molar mass of approximately 12g/mol, we can use the formula: number of atoms = (mass of substance / molar mass) x Avogadro's number. Plugging in the values, we get (6g / 12g/mol) x 6.02 x 10^23, which simplifies to 3.01 x 10^23 atoms.

The molecular formula of Vitamin-A is C20H30O, which means that it contains 20 carbon atoms, 30 hydrogen atoms, and 1 oxygen atom. To calculate the number of molecules in 500 mg of its capsule, we need to convert the mass of the capsule to moles using the molar mass of Vitamin-A. The molar mass of Vitamin-A can be calculated by adding the atomic masses of carbon, hydrogen, and oxygen. Once we have the number of moles, we can use Avogadro's number (6.02 x 10^23) to calculate the number of molecules. The correct answer, 1.05 x 10^21, is obtained by correctly performing these calculations.

When one mole of each substance is burnt in oxygen, the substance that will produce the largest mass of CO2 is ethane. This is because ethane (C2H6) has two carbon atoms, while the other substances have only one carbon atom. Since the number of carbon atoms directly affects the amount of CO2 produced, ethane will yield a larger mass of CO2 compared to the other substances.

The complete combustion of butane (C4H10) requires 13 moles of oxygen. This can be determined by balancing the chemical equation for the combustion of butane, which is C4H10 + 13O2 -> 8CO2 + 10H2O. The equation shows that for every 1 mole of butane, 13 moles of oxygen are needed to produce 8 moles of carbon dioxide and 10 moles of water. Therefore, for 2 moles of butane, we would need 2 x 13 = 26 moles of oxygen.

The given question asks for the incorrect statement among the options. The correct answer is "None of above," which means that all of the statements are correct. This implies that 12 g of carbon gas does contain one mole of atoms, 28 g of nitrogen gas contains one mole of molecules of N2, and 1 dm3 of 1.0 mole dm-3 solution of NaCl does contain one mole of chloride ions.

One mole of any substance is equal to its molar mass in grams. The molar mass of iodine (I2) is approximately 254 g/mol. Therefore, the mass of one mole of iodine molecules is 254 g.