I need help (ima add another question with the student guide i did)

7. what temperature is need to just dissolve 50 g of nh4cl in 75 g of water? '

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

Why is retrograde motion an apparent motion