Given a solution of a mass of 200 g with a mass fraction of 2% salt. Find the mass of dissolved salt.

Given:
m solution (salt) = 200 g
ω (salt) = 2%

To find:
m (salt) -?

Decision:
1) The initial formula for finding the mass fraction of salt in solution:
ω (salt) = m (salt) * 100% / m solution (salt);
2) Using the original formula, calculate the mass of salt in the solution:
m (salt) = ω (salt) * m solution (salt) / 100% = 2% * 200/100% = 4 g.

Answer: The mass of the dissolved salt is 4 g.