Im assuming, if you find rare earth elements, it is important to the technological world bc you can make more products more better, and even invent new and more modern things.
Part 1 :- Super gaint star have mass from 10 to 70 solar masses and brightness from 30,000 upto hundreds of thousand times the solar luminosity
blue super giant surface temperature is 20,000 to 50,000 degree Celsius example :0 Rigel its mass is around 20 times the sun mass it give light which 60,000 sun together give .
part 2 :- HR diagram : hertzsprung -Russel diagram ( attached below)

is aluminium oxide (also called aloxide, aloxite and alundum). It is neither acid nor base. It has amphoteric nature meaning it can act as an acid with bases and as a base with acids. It neutralises them to salts.
Answer:
1
Explanation:
fluorine's atomic number is 9
electronic configuration: 2,7
so it needs 1 electron to stabilise
that's why 1 covalent bond
hope it helps!!
Answer:
[Ag⁺] = 5.0x10⁻¹⁴M
Explanation:
The product solubility constant, Ksp, of the insoluble salts PbI₂ and AgI is defined as follows:
Ksp(PbI₂) = [Pb²⁺] [I⁻]² = 1.4x10⁻⁸
Ksp(AgI) = [Ag⁺] [I⁻] = 8.3x10⁻¹⁷
The PbI₂ <em>just begin to precipitate when the product [Pb²⁺] [I⁻]² = 1.4x10⁻⁸</em>
<em />
As the initial [Pb²⁺] = 0.0050M:
[Pb²⁺] [I⁻]² = 1.4x10⁻⁸
[0.0050] [I⁻]² = 1.4x10⁻⁸
[I⁻]² = 1.4x10⁻⁸ / 0.0050
[I⁻]² = 2.8x10⁻⁶
<h3>[I⁻] = 1.67x10⁻³</h3><h3 />
So, as the [I⁻] concentration is also in the expression of Ksp of AgI and you know concentration in solution of I⁻ = 1.67x10⁻³M:
[Ag⁺] [I⁻] = 8.3x10⁻¹⁷
[Ag⁺] [1.67x10⁻³] = 8.3x10⁻¹⁷
<h3>[Ag⁺] = 5.0x10⁻¹⁴M</h3>