Que cantidad de impurezas tendrá un anillo de 14 kilates que pesa 15 gramos

6.25 g

Explanation:

Pure gold is 24K.

If gold is 14K, it is 14/24 pure.

The remaining 10/24 is usually some other metal added to the gold to give it desired properties.

In a 14K ring with a mass of 15 g, the mass of "impurities" is

10/24 * 15 g = 6.25 g