I had a tooth extraction of a decayed molar 4 days ago. is white yellowish color on top of the clot normal? or should i fear dry socket.

No problem: Normal healing process. As long as it is covered no worries about dry socket. Dry socket occurs when clot is lost and socket is empty and open, then must heal from bottom

Normal color: Seeing a white yellowish color in the socket is a normal healing site inside the mouth. It would look like a scab if on the outside. A dry socket can have some of this color but usually red and inflammed on outside with dark open socket. It would be painful, more intense, foul odor. Call your dentist if you have concerns.

You are fine: That is part of the normal healing process. You will know if you have dry socket as you will be in extreme pain. If you have any concerns, see your dentist.

You are doing fine!: Believe me you would know if you had a dry socket! typically with a dry socke, you would have extreme pain all of a sudden after you were feeling better prior to that. Keep the area clean by gently rinsing after every time you eat or snack so it will heal quicker.