Mole Concept And Molar Masses

To arrange the given solutions in order of decreasing molarity, we must first understand the concept of molarity. Molarity ( ) is defined as the number of moles of solute per liter of solution. The formula for molarity is:

Since each solution is prepared by dissolving 1 g of solute in 1 L of solution, the volume of the solution is the same for all, equal to 1 L. Hence, molarity can be calculated as:

• For Glucose (A):
  Molar mass = 180 g/mol
  Molarity = mol/L
• For NaOH (B):
  Molar mass = 40 g/mol
  Molarity = mol/L
• For NaCl (C):
  Molar mass = 58.5 g/mol
  Molarity = mol/L
• For KCl (D):
  Molar mass = 74.5 g/mol
  Molarity = mol/L

To arrange them in decreasing order of molarity, we compare the values:

• (NaOH) > (NaCl) > (KCl) > (Glucose)

Thus, the decreasing order of molarity is: (B), (C), (D), (A).

However, looking at the options provided, it seems there's a mismatch between calculated result and options given. Based on offered options and given correct answer, the question context might have variations or assumptions not directly matching simple calculation seen. Review or realignment on problem statement basis may be necessary for further peri-analysis beyond basic introductory calculation approach here.

To calculate the molality of KI in a 20% (mass/mass) aqueous solution of KI, follow the steps below:

Understand the Definitions:

• The density of the solution is given as .
• A 20% (mass/mass) solution means 20 g of KI is present in every 100 g of solution.
• Molality is defined as the number of moles of solute per kilogram of solvent.

Calculate the Mass of Solvent:

• 20% (w/w) means 20 g KI and 80 g of water (since 100 g - 20 g = 80 g of solvent).

Calculate the Number of Moles of KI:

• The molar mass of KI is given as .
• The number of moles of KI in 20 g of KI is calculated as:
  

Convert Mass of Solvent to Kilograms:

• Convert 80 g to kg:
  

Calculate the Molality:

• Molality is calculated using the formula:
  
• Substitute the calculated values:
  

The closest option to our calculated molality is (1) 5 mol kg^-1, implying either an error in calculation or a misinterpretation of density. However, this value doesn't align, meaning there might be an error in the provided options as correctly calculated value using provided data yields approximately 1.506 mol kg^-1.

To solve this matching question related to the concepts of conductivity in chemistry, we will identify the correct matches based on the definitions and units of the terms provided in List-I and List-II.

1. Cell constant (A - I): The cell constant is a geometrical factor that relates to the setup of the conductivity cell. It is defined as the ratio of the distance between the electrodes to the area of cross-section of the electrodes. The unit of cell constant is .
2. Molar conductance (B - II): Molar conductance refers to the conductance of an electrolyte solution divided by its concentration, normalized to one mole of electrolyte. It has the unit .
3. Specific conductance (C - III): Also known as conductivity, specific conductance is the conductance of a solution of unit length and unit cross-sectional area. Its unit is .
4. Conductance (D - IV): Conductance is a measure of how easily electricity flows through a material. It is the reciprocal of resistance, and its unit is .

From the above analysis, the correct matches from List-I to List-II are:

• (A) Cell constant - (I)
• (B) Molar conductance - (II)
• (C) Specific conductance - (III)
• (D) Conductance - (IV)

The correct answer is therefore (A) - (I), (B) - (II), (C) - (III), (D) - (IV).

To determine the order of the number of molecules contained in 16 g of each compound, we need to calculate the number of moles for each and then use Avogadro's number to find the actual number of molecules. We use the formula:

Now, convert moles to number of molecules using Avogadro's number, .

• : molecules
• : molecules
• : molecules
• : molecules

Arranging in decreasing order, the number of molecules is: .
Therefore, the correct arrangement is:

D>A>C>B