A bucket of water is hanging from a spring balance. An iron piece is suspended into water without touching sides of bucket from another support. The spring balance reading will

When an iron piece is suspended into the water without touching the sides of the bucket, the volume of water displaced by the iron piece is equal to the volume of the iron piece submerged. According to Archimedes' principle, the buoyant force acting on the iron piece (equal to the weight of the water displaced) is equal to the weight of the iron piece itself. Therefore, the net effect on the spring balance due to the addition of the iron piece is zero, and the reading of the spring balance will remain the same.