Some basic concepts of chemistry practice · Mixed difficulty

Option B is correct. Both the assertion and the reason are true, but the reason is not the correct explanation for the assertion. The percentage of nitrogen in urea is 46.6%, and urea is a covalent compound, but the covalent nature doesn't explain the nitrogen percentage.

Option A (5,6,3,3) is correct because it represents the stoichiometric coefficients that balance the redox reaction.

The correct answer is A (Law of conservation of mass) because the reaction demonstrates that the total mass of reactants equals the total mass of products.

Option B (40 and 30) is correct because solving the system of equations derived from the molar masses of the compounds yields these atomic weights.

Option B (10.6 g) is correct because the weight of 0.1 mole of $Na_2CO_3$ is calculated by multiplying the number of moles by the molar mass.

Option C (2.8) is correct because it is the calculated weight of KOH based on its milli-equivalent weight.

Option C (22.4) is correct because the mass of oxygen is calculated based on the molar mass of the compound and the number of oxygen atoms present.

Option D ($2 \times N_A$) is correct because each Al3+ ion has 10 electrons, and 0.2 moles of Al3+ ions will therefore have 2NA electrons.

Option B (110.2) is correct because the change in standard entropy is calculated using the formula $\Delta G^{\circ}=\Delta H^{\circ}-T \Delta S^{\circ}$.

Option A (If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion) is correct because the definition of molality directly explains why a 1 molal glucose solution contains 180g of glucose in 1 kg of water.

Option C ($6.02 \times 10^{24}$) is correct because 18 mL of water is 1 mole, and each water molecule has 10 electrons.

Option B (5) is correct because the value of x is calculated using the vapor density formula and the given molecular formula.

The correct answer is D (1.0 M) because the molarity is calculated by dividing the moles of solute by the volume of the solution in liters.

Option B (1.12 L) is correct because it is the volume of CO2 produced from the complete decomposition of 9.85 g of BaCO3, calculated using stoichiometry.

Option B ($0.33$) is correct because it is the normality of the solution calculated using the given mass of ${\mathrm{H}_3}\mathrm{P}{\mathrm{O}_4}$ and volume of the solution.

Option B (2.16 g) is correct because it is calculated using stoichiometry based on the amount of AgCl precipitated.

Option A (0.1 mole of $\mathrm{C}{\mathrm{O}_2}$ gas) is correct because it represents the smallest number of moles, and equal numbers of moles have equal numbers of molecules.

Option A (0.5) is correct because 49 g of H2SO4 contains 0.5 g-atom of S, calculated based on the molar mass of H2SO4 and the atomic mass of S.

Option B (11.6 g) is correct because it is calculated based on the stoichiometry of the reaction and the molar masses of the compounds involved.

Option B (Both A and R are correct, but R is not the correct explanation of A) is correct because both statements are factually correct, but the reason doesn't explain the assertion.

Option C is correct because both the assertion and reason are correct, and the reason accurately explains why the listed concentration units are independent of temperature.

Option D (Definite proportion) is correct because the law of constant composition is another name for the law of definite proportions.

Option A (0.167) is correct because it is the calculated mole fraction of the solute in the aqueous solution with a molality of 11.11.

Option C ((A) is true but (R) is false) is correct because the percentage of nitrogen in urea is indeed 46.6%, but urea is a covalent, not ionic, compound.

Option B (36.9%) is correct because the percentage loss in mass is calculated based on the molar mass of the gases released (CO₂ and H₂O) relative to the molar mass of NaHCO₃.

Option B (24) is correct because it correctly calculates the atomic weight of the divalent metal using the concept of equivalent weights.

Option D (0.5) is correct because the percentage purity is calculated by comparing the actual yield of $Cl_2$ to the theoretical yield based on the amount of $MnO_2$ used.

Option D is correct because the milliequivalents of NaOH and H2SO4 are equal, resulting in a neutral solution, making the assertion false, but the reason is true.

Option A ($1g\,\,of\,C{O_2}\left( g \right)$) is correct because it contains the least number of atoms when considering the molar mass and atomicity of each compound.

Option B (${C}^{12}$) is correct because the modern atomic weight scale is based on the carbon-12 isotope, which is assigned an atomic mass of exactly 12 atomic mass units.