Na2SO3” represents sodium sulfite. What does the 4 mean in the formula 4Na2SO3?

There are four atoms of sodium.
There are four atoms of sodium sulfite.
There are four molecules of sodium sulfite.
There are four elements in sodium sulfite.
PLEASE HELP I ONLY HAVE 30MIN and i have a test today and i will be happy if you help me :)

What is the energy of a photon of ultraviolet radiation with a frequency of 4.4 × 1015 hz? planck’s constant is 6.63 × 10–34

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