Question

tell some information about platinum-iridium international prototype cylinder​

Answer 1

Answer:

The IPK is a roughly golfball-sized object made of a platinum alloy known as "Pt‑10Ir", which is 90% platinum and 10% iridium (by mass) and is machined into a right-circular cylinder with height equal to its diameter of about 39 millimetres to reduce its surface area.