Answer:
pH = 4.09
Explanation:
molarity of oxalic acid in the solution
= 0.1 x 25 / (25 + 35)
= 0.0417 M
molarity of NaOH in the solution
= 0.1 x 35 / (25 +35)
= 0.0583 M
H2C2O4 + NaOH -------------------> NaHC2O4 + H2O
0.0417 0.0583 0 0
0 0.0166 0.0417
now second acid -base titration
NaHC2O4 + NaOH -------------------> Na2C2O4 + H2O
0.0417 0.0166 0 0
0.0251 0 0.0166 ---
now
pH = pKa2 + log [Na2C2O4 / NaHC2O4]
pH = 4.27 + log (0.0166 / 0.0251)
pH = 4.09
Answer: B. a chemical change
Explanation:
There are 1.93 x 10²⁴ particles
<h3>Further explanation</h3>
Given
3.2 moles of Neon gas
Required
Number of particles
Solution
The mole is the number of particles(molecules, atoms, ions) contained in a substance
<em>1 mol = 6.02.10²³ particles
</em>
Can be formulated
N=n x No
N = number of particles
n = mol
No = Avogadro's = 6.02.10²³
So the number of particles for 3.2 moles :
N = 3.2 x 6.02.10²³
N = 1.93 x 10²⁴
or
we can describe it using Avogadro's number conversion factor

1.905 moles of Helium gas are in the tube. Hence, option A is correct.
<h3>What is an ideal gas equation?</h3>
The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).
Calculate the moles of the gas using the gas law,
PV=nRT, where n is the moles and R is the gas constant. Then divide the given mass by the number of moles to get molar mass.
Given data:
P= 4.972 atm
V= 9.583 L
n=?
R= 
T=31.8 +273= 304.8 K
Putting value in the given equation:
=n
n= 
Moles = 1.905 moles
1.905 moles of Helium gas are in the tube. Hence, option A is correct.
Learn more about the ideal gas here:
brainly.com/question/27691721
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