Answer:
The correct answer to the following question will be "4.08 × 10⁻¹⁹ Joule".
Explanation:
Given:
Wavelength, λ = 486.0 nm
As we know,

On putting the estimated values, we get
⇒ 
⇒ 
∴ 1 ev = 1.6 × 10⁻¹⁹ J
Now,
Energy, 
⇒ 
You convert kinetic energy into thermal energy when you rub two sticks together.
How many moles of oxygen atoms are present in 5
moles of Mg3(PO4)2
All you have to do is to create
a ratio between the molecule and the oxygen atom.
5 moles of Mg3(PO4)2 (4x2 moles
O/1 mole Mg3(PO4)2) = 40 moles of oxygen