5 ml of (m/10) HCl
10 ml of (m/10) HCl
15 ml of (m/5) HCl
20 ml of (m/8) HCl
Explanation
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PH only depends on concentration, so the volume they are showing there is just for decoration, it doesn't affect the PH
Option A
Concentration = m/10 = 0.1M
PH = -log 0.1 = 1
Option
It has the same concentration as Option A, therefore it has the same PH. It doesn't matter if you have one litre of 1M HCl or ten litres of 1M HCl they will both have the same PH.
Option C
Concentration = M/5 = 0.2M
PH = -log 0.2 = 0.7
Option D
Concentration = M/8 = 0.125M
PH = -log 0.125 = 0.9
The one with the lowest PH here is option C, if you disagree, then go and read this topic again thoroughly. I'm so shocked that no one got the correct answer.
To determine which solution has the lowest pH value, we need to compare the concentrations of H+ ions in each solution.
The pH of a solution is defined as the negative logarithm (base 10) of the concentration of H+ ions in moles per liter (pH = -log[H+]). The lower the pH value, the higher the concentration of H+ ions, and the more acidic the solution.
The concentration of H+ ions in each solution:
A. 5 ml of (m/10) HCl:
1 liter of (m/10) HCl contains 0.1 moles of HCl.
Therefore, 5 ml of (m/10) HCl contains (0.1/1000) x 5 = 0.0005 moles of HCl.
Since HCl is a strong acid, it completely dissociates in water to produce H+ and Cl- ions in a 1:1 ratio.
So the concentration of H+ ions in this solution is 0.0005 moles/liter.
pH = -log[H+] = -log(0.0005) = 3.3
B. 10 ml of (m/10) HCl:
1 liter of (m/10) HCl contains 0.1 moles of HCl.
Therefore, 10 ml of (m/10) HCl contains (0.1/1000) x 10 = 0.001 moles of HCl.
Since HCl is a strong acid, it completely dissociates in water to produce H+ and Cl- ions in a 1:1 ratio.
So the concentration of H+ ions in this solution is 0.001 moles/liter.
pH = -log[H+] = -log(0.001) = 3.0
C. 15 ml of (m/5) HCl:
1 liter of (m/5) HCl contains 0.2 moles of HCl.
Therefore, 15 ml of (m/5) HCl contains (0.2/1000) x 15 = 0.003 moles of HCl.
Since HCl is a strong acid, it completely dissociates in water to produce H+ and Cl- ions in a 1:1 ratio.
So the concentration of H+ ions in this solution is 0.003 moles/liter.
pH = -log[H+] = -log(0.003) = 2.5
D. 20 ml of (m/8) HCl:
1 liter of (m/8) HCl contains 0.125 moles of HCl.
Therefore, 20 ml of (m/8) HCl contains (0.125/1000) x 20 = 0.0025 moles of HCl.
Since HCl is a strong acid, it completely dissociates in water to produce H+ and Cl- ions in a 1:1 ratio.
So the concentration of H+ ions in this solution is 0.0025 moles/liter.
pH = -log[H+] = -log(0.0025) = 2.6
Therefore, the solution with the lowest pH value is C. 15 ml of (m/5) HCl, with a pH of 2.5. This is because it has the highest concentration of H+ ions (0.003 moles/liter) compared to the other solutions.
Therefore, option C, 15 ml of (m/5) HCl, has the lowest pH value, and is the most acidic solution among the given choices.
Yea,A is the answer,cos from optn A 5*m/10=m/2,B 10*M/10=m,C 15*M/5=3M,D 20*m/8=5m/2,let m be 4.or u can take any nos we get 2,4,12 and 10,so i think optn A has the lowest value 2
The selected answer is wrong:
n= cv, pH=-log[H^+]
for A,
n= (5/1000)dm^3 x (1/10)moledm^-3= 5x10^-4mole
pH= -[log5 x log10^-4]= 3.3
for B,
n=(10/1000)dm^3 x (1/10)moledm^-3= 1x10^-3mole
pH= -[log1 xlog10^-3]= -[0+(-3)]= 3
for C,
n= (20/1000)dm^-3 x(1/8)moledm^-3= 2.5x10^-3mole
pH= -[log2.5 x log10^-3]= 2.6
for D,
n= (15/1000)dm^3 x (1/2)moledm^-3= 7.5x10^-3mole
pH= -[log7.5 x log10^-3]= 2.1
from the above we see that option D has the lowest pH.
i humbly crave on you to change the answer and upload this explanation @myschool
merci !!!
