The formula that would represent an ionic compound that is composed of calcium and iodide ions is CaI2
Explanation
Ionic compound CaI₂ is formed when Calcium form cation ( <em>a positively charged ion</em>) by losing 2 electrons while two iodine atoms form anion ( <em>a negatively charged ion</em>) by gaining one electron each.
When writing down formula of ionic compound, the formula of cation is written first followed by anion formula. therefore Ca is written first followed by I.
The numeric subscript 2 after I(iodine) indicate that 2 atoms of iodine are involved in bonding.
Wavelength of the light is 2.9 × 10⁻⁷ m.
<u>Explanation:</u>
Planck - Einstein equation shows the relationship between the energy of a photon and its frequency, and they are directly proportional to each other and it is given by the equation as E = hν,
where E is the energy of the photon
h is the Planck's constant = 6.626 × 10⁻³⁴ J s
ν is the frequency
From the above equation, we can find the frequency by rearranging the equation as,
ν = 
= 
Now the frequency and the wavelength are in inverse relationship with each other.
ν × λ = c
It can be rearranged to get λ as,
λ = c / ν
= 
So wavelength is 2.9 × 10⁻⁷ m.
Answer: “We live on a hunk of rock and metal that circles a humdrum star that is one of 400 billion other stars that make up the Milky Way Galaxy which is one of billions of other galaxies which make up a universe which may be one of a very large number, perhaps an infinite number, of other universes. That is a perspective on human life and our culture that is well worth pondering.”
― Carl Saga
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