Answer:
good question..... lemme think now LOL
212 ml of lead nitrate is required to prepare a dilute solution of 820.7 ml of lead nitrate.
Answer:
Option A.
Explanation:
Similar to Avagadro's law, there is another law termed as dilution law. As the product of volume and normality of the reactant is equal to the product of volume and normality of the product from the Avagadro's law. In dilution law, it will be as product of volume and concentration of the solute of the reactant is equal to the product of volume and concentration of solution.

So, as per the given question C1 = 5.45 M of lead nitrate and V1 has to be found. While C2 is 1.41 M of lead nitrate and V2 is 820.7 ml.
Then, 

So nearly 212 ml of lead nitrate is required to prepare a dilute solution of 820.7 ml of lead nitrate.
Answer:
4.419 g
Explanation:
55 years is 5.5 half lives
200 g * (1/2)^5.5 = 4.419 g
Answer:
The enthalpy change during the reaction is -199. kJ/mol.
Explanation:

Mass of solution = m
Volume of solution = 100.0 mL
Density of solution = d = 1.00 g/mL

First we have to calculate the heat gained by the solution in coffee-cup calorimeter.

where,
m = mass of solution = 100 g
q = heat gained = ?
c = specific heat = 
= final temperature = 
= initial temperature = 
Now put all the given values in the above formula, we get:


Now we have to calculate the enthalpy change during the reaction.

where,
= enthalpy change = ?
q = heat gained = 2.242 kJ
n = number of moles fructose = 

Therefore, the enthalpy change during the reaction is -199. kJ/mol.