Answer:
3.51
Explanation:
Before any sodium hydroxide has been added, the pH is that of the aqueous hydrofluoric acid solution.
HF is a weak acid that dissociates according to the following equation.
HF(aq) ⇄ H⁺(aq) + F⁻(aq) Ka = 6.76 × 10⁻⁴
We can find [H⁺] using the following expression.
[H⁺] = √(Ca × Ka)
where
Ca: concentration of the acid
Ka: acid dissociation constant
[H⁺] = √(Ca × Ka)
[H⁺] = √(0.458 × 6.76 × 10⁻⁴)
[H⁺] = 3.10 × 10⁻⁴ M
The pH is:
pH = -log [H⁺]
pH = -log 3.10 × 10⁻⁴ = 3.51
Answer:
Both sodium and calcium.
Explanation:
The membrane potential is maintained inside and outside of the cell due to the unequal distribution of the different ions. This membrane potential difference is important for the generation of action potential.
The resting membrane potential is around +30 mV. This is due to the presence of potassium ions. The sodium and calcium ions must enter in the cell to change this membrane potential and generates the action potential in the body.
Thus, the correct answer is option (3).
Density
=mass÷volume
=277÷38
=7.29 g/cm3
The electrons are unequally shared. The electronegative element receives the electrons from the electropositive one.
207 is the mass number. 82 would be the atomic number
