Answer:
9.88
Explanation:
As higher is the Ksp, more soluble is the compound. So, Co(OH)₂ is the less soluble hydroxide.
The maximum concentration of it must be 1x10⁻⁶ M, and the reaction is:
Co(OH)₂(s) ⇄ Co⁺²(aq) + 2OH⁻(aq)
So, [Co⁺²] = 1x10⁻⁶M
Ksp = [Co⁺²] *[OH⁻]²
[OH⁻]² = 5.9x10⁻¹⁵/1x10⁻⁶
[OH⁻] = √(5.9x10⁻⁹)
[OH⁻] = 7.6811x10⁻⁵
pOH = -log[OH⁻]
pOH = -log(7.6811x10⁻⁵)
pOH = 4.11
Knowing that pH + pOH = 14
pH = 14 - 4.11
pH = 9.88
Answer: Option (b) is the correct answer.
Explanation:
It is given that mass of Mg is 97.22 g and it is known that molar mass of Mg is 24.305 g/mol.
So, calculate the number of moles as follows.
No. of moles = 
=
= 4 mol
Also, it is known that 1 mole has
atoms/mol. Therefore, calculate the number of atoms in 4 mol as follows.

=
atoms
or, =
atoms
Thus, we can conclude that there are
atoms in 97.22 grams of Mg.
Answer:

Explanation:
Hello,
In this case, for each nitrate-based salt, we compute the nitrate moles as shown below:



We notice calcium nitrate has two moles of nitrate ion, sodium nitrate has one and aluminium nitrate has three. Hence we add the moles to obtain the total moles nitrate ion:

Finally, we compute the molarity:

Regards.
Answer:
B) 2
Explanation:
Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
The rule apply for the multiplication and division is :
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
The rule apply for the addition and subtraction is :
The least precise number present after the decimal point determines the number of significant figures in the answer.
(3.478-2.31) = 1.168 ≅ 1.17 (Rounded to least decimal digit)
(4.428-3.56) = 0.868 ≅ 0.87 (Rounded to least decimal digit)
So,
1.17 * 0.87 = 1.0 (Rounded to least significant)
Answer - two significant digits
O2=32 g/ mol
1.15/32=0.035
N2=28 g/mol
1.55/28=0.055
in STP every 22.4 litters is 1 mol