Answer:
because the number of electrons and protons differs
The given question is incomplete. The complete question is :
Which of the following Group 17 elements is the least reactive
a) Flourine
b) Chlorine
c) Astatine
d) Iodine
Answer: c) Astatine
Explanation:
Halogen is the name given to Group 17 family with general electronic configuration of
which have 7 valence electrons and thus easily gain one electron to attain stable configuration.
As we move down the group from flourine to chlorine to bromine to iodine to astatine , the valence shell moves farther from nucleus and thus tendency to accept the electron decreases and thus reactivity also decreases.
Thus Astatine is the least reactive of all.
The rate of effusion of H₂ : 7.2 x 10⁻² m/s
<h3>Further explanation </h3>
Graham's law: the rate of effusion of a gas is inversely proportional to the square root of its molar masses or
the effusion rates of two gases = the square root of the inverse of their molar masses:

or

MW₁ O₂ = 32 g/mol
MW₂ H₂ = 2 g/mol

Answer:
Well its not gonna work anymore and you will be able to all the wires in the earphones!
Explanation:
Answer : The pH will be, 3.2
Explanation :
As we known that the value of solubility constant of ferric hydroxide at
is, 
Amount or solubility of iron consumed = (1.800 - 0.3) mg/L = 1.5 mg/L
The given solubility of iron convert from mg/L to mol/L.

The chemical reaction will be:

The expression of solubility constant will be:
![K_{sp}=[Fe^{3+}]\times [3OH^-]^3](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BFe%5E%7B3%2B%7D%5D%5Ctimes%20%5B3OH%5E-%5D%5E3)
Now put all the given values in this expression, we get the concentration of hydroxide ion.
![2.79\times 10^{-39}=(2.7\times 10^{-7})\times [3OH^-]^3](https://tex.z-dn.net/?f=2.79%5Ctimes%2010%5E%7B-39%7D%3D%282.7%5Ctimes%2010%5E%7B-7%7D%29%5Ctimes%20%5B3OH%5E-%5D%5E3)
![[OH^-]=1.5\times 10^{-11}M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.5%5Ctimes%2010%5E%7B-11%7DM)
Now we have to calculate the pOH.
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)


Now we have to calculate the pH.

Therefore, the pH will be, 3.2