The formula for kinetic energy is KE=1/2(mv²). Since both mass and velocity are multiplied by each other, particle with a larger mass needs to be moving slower than a particle with less mass if both have the same kinetic energy. You can think of it as 2KE/m=v² or 2KE/v²=m, If you increase the mass the velocity needs to decrease to keep the same KE value.
I hope this helps. Let me know in the comments if anything is unclear.
The molar concentration of the original HF solution : 0.342 M
Further explanation
Given
31.2 ml of 0.200 M NaOH
18.2 ml of HF
Required
The molar concentration of HF
Solution
Titration formula
M₁V₁n₁=M₂V₂n₂
n=acid/base valence (amount of H⁺/OH⁻, for NaOH and HF n =1)
Titrant = NaOH(1)
Titrate = HF(2)
Input the value :

Use the periodic table , it should be the long decimal if u look it up
The weight/weight percent(%w/w) of NaCl in solution : 33.03%
<h3>Further explanation</h3>
Given
Mole fraction of NaCl : 0.132
Required
The weight/weight percent of NaCl
Solution
1 mol solution : 0.132 mol NaCl + 0.868 mol H₂O
mass NaCl :

mass H₂O :

Total mass = 7.714 + 15.64 = 23.354 g
