Explanation:
Initial mass of the isotope 90-Sr in baby= 1.00 μg
Formula used :

where,
= initial mass of isotope
N = mass of the parent isotope left after the time, (t)
= half life of the isotope = 28.1 years
= rate constant

a) Time taken by the sample, t = 18 years


0.6415 μg will remain after 18 years.
b) Time taken by the sample, t = 70 years


0.1779 μg will remain after 70 years.
Answer : The specify the l and ml values for n = 4 are:
At l = 0, 
At l = 1, 
At l = 2, 
At l = 3, 
Explanation:
There are 4 quantum numbers :
Principle Quantum Numbers : It describes the size of the orbital. It is represented by n. n = 1,2,3,4....
Azimuthal Quantum Number : It describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For l = 0,1,2,3... the orbitals are s, p, d, f...
Magnetic Quantum Number : It describes the orientation of the orbitals. It is represented as m_l. The value of this quantum number ranges from
. When l = 2, the value of
will be -2, -1, 0, +1, +2.
Spin Quantum number : It describes the direction of electron spin. This is represented as
The value of this is
for upward spin and
for downward spin.
As we are given, n = 4 then the value of l and ml are,
l = 0, 1, 2, 3
At l = 0, 
At l = 1, 
At l = 2, 
At l = 3, 
Answer:
Molar solubility is 1.12x10⁻⁴M
Explanation:
The dissolution of magnesium hydroxide is:
Mg(OH)₂(s) ⇄ Mg²⁺ + 2OH⁻
The molar solubility represents the moles of the solid that the solution can dissolve, that could be written as:
Mg(OH)₂(s) ⇄ X + 2X
<em>Where X is solubility.</em>
<em />
If you obtained a [OH⁻] = 2.24x10⁻⁴M and you know [OH⁻] = 2X:
2X = 2.24x10⁻⁴M
X = 2.24x10⁻⁴M/2
X =1.12x10⁻⁴M
<h3>Molar solubility is 1.12x10⁻⁴M</h3>
As water freezes its molecules move farther apart. As when water freezes , Its move farther apart .
And the cause of this movement is hydrogen bond that is formed among the surrounding water molecules that causes water molecules to move apart. So as water freezes its molecules move farther apart, it is the correct answer .