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Answer:
A. {K}, {Ba}, {Ca}, {Na}
B. {Au}
C. {Na}
D. Image Missing
Explanation:
PART A:
The range of wavelengths in visible region is 380 nm to 740 nm. Thus, all the elements that emit light of wavelength in this region are the elements which emit radiation in visible part. They are:
{k}
{Ba}
{Ca}
{Na}
PART B:
The energy of a photon is inversely proportional to its wavelength (E = hc/λ). Therefore, the element, which emits the radiation of smallest wavelength, has the highest energy photons. <u>That element is {Au}</u>
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PART C:
Similarly, the element which emits radiation of highest wavelength, has the lowest energy. <u>That element is {Na}</u>
PART D:
Image missing.
Answer:
pH = 12.2
Explanation:
Given data:
Mass of lime = 0.69 g
Volume = 1535 mL (1535 / 1000 = 1.535 L)
pH of solution = ?
Solution:
First of all we will determine the molarity.
Molarity = moles of solute / volume in litter
Number of moles = mass / molar mass
Number of moles = 0.69 g / 56.1 g/mol
Number of moles = 0.0123 mol
Molarity = moles of solute / volume in litter
Molarity = 0.0123 mol / 1.535 L
Molarity = 0.008 M
One mole of CaO neutralize two mole of OH⁻.
0.008 M×2 = 0.016 M
[OH⁻] = 0.016 M
pOH = -log [OH⁻]
pOH = [0.016]
pOH = 1.8
14 = pH +pOH
pH = 14 - pOH
pH = 14-1.8
pH = 12.2
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