dimensional analysis
periodic table
100

This element name is Sb.

What is antimony?

200

This element is in column 4 and period 6.

What is Chromium?

300

Find the wavelength when it has an energy of 4.20×10−19 J.

answer in nanometers. 

(10^−9m=1nm)

E = hc/λ

What is 473 nanometers?

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