Chemistry

The partial pressure of dry N? is 758 - 14 = 744 mm Hg. Using the ideal gas law (PV=nRT), the moles of N? are calculated to be 1.25 * 10? ³ mol. This corresponds to 0.035 g of N? The percentage of nitrogen in the sample is (0.035 g / 0.1840 g) * 100, which is 18.96%.
Answer: 19 (Rounded)

This is a limiting reactant problem. The initial moles are 5.25 mmol of Pb (NO? )? and 2.4 mmol of Cr? (SO? )? Based on the 3:1 stoichiometric ratio, Pb (NO? )? is the limiting reactant. The moles of PbSO? formed are equal to the initial moles of the limiting reactant, which is 5.25 mmol or 5.25 * 10? ³ moles. The question asks for the answer in units of 10? moles.

First, the number of unit cells in the given mass is determined. In an HCP structure, there are 6 atoms and 18 total voids (6 octahedral + 12 tetrahedral) per unit cell. Multiplying the number of unit cells by 18 gives the total number of voids. The result is14.9 x 10²¹, which is rounded.

Using the integrated rate laws for both reactions and solving for time 't' yields a value of 108.

Kindly go through the solution

Urea-formaldehyde resin is used for wood laminates because of its durable and unbreakable properties.

This problem involves the stoichiometry of acid-base neutralization.

o   For the reaction with H? PO? (a dibasic acid), 100 mL of NaOH is required.

o   For the reaction with H? PO? (a monobasic acid), 200 mL of NaOH is required.

In proteins, the secondary structure (such as α-helices and β-sheets) is stabilized by hydrogen bonds formed between the carbonyl oxygen of one peptide bond and the amide hydrogen of another.

The magnetic moment of an ion is determined by its number of unpaired electrons (n). For the given lanthanide ions:

o   Ce? has 0 unpaired electrons (4f? ).

o   Eu³? has 6 unpaired electrons (4f? ).

o   Gd³? has 7 unpaired electrons (4f? ).
Gd³? has the highest number of unpaired electrons and therefore the highest magnetic moment.