246 g KMnO4
Mass = 38.5 g water × (6.38 g KMnO4/100 g water) = 246 g KMnO4
The number of atoms : N = 2.709 x 10⁴⁶
<h3>Further explanation</h3>
Given
4.5 x 10²² moles of CO₂
Required
The number of atoms
Solution
The mole is the number of particles(molecules, atoms, ions) contained in a substance
1 mol = 6.02.10²³ particles
Can be formulated
N=n x No
N = number of particles
n = mol
No = Avogadro's = 6.02.10²³
Input the value :
N = 4.5 x 10²² x 6.02 x 10²³
N = 2.709 x 10⁴⁶
Answer : The molal freezing point depression constant of X is 
Explanation : Given,
Mass of urea (solute) = 5.90 g
Mass of X liquid (solvent) = 450.0 g
Molar mass of urea = 60 g/mole
Formula used :

where,
= change in freezing point
= freezing point of solution = 
= freezing point of liquid X= 
i = Van't Hoff factor = 1 (for non-electrolyte)
= molal freezing point depression constant of X = ?
m = molality
Now put all the given values in this formula, we get
![[0.4-(-0.5)]^oC=1\times k_f\times \frac{5.90g\times 1000}{60g/mol\times 450.0g}](https://tex.z-dn.net/?f=%5B0.4-%28-0.5%29%5D%5EoC%3D1%5Ctimes%20k_f%5Ctimes%20%5Cfrac%7B5.90g%5Ctimes%201000%7D%7B60g%2Fmol%5Ctimes%20450.0g%7D)

Therefore, the molal freezing point depression constant of X is 
The sodium in soda lowers the melting point and makes the ice melt more slowly than it would in plain water because with the addition of any substance, there are fewer free water molecules available to form bonds together and freeze
Answer:
Thermometer A, because it measures accurately to the tenths digit.