Question

A goldsmith desires to test the purity of a gold ornament suspected to the mixed with copper.The ornament weights 0.25 kg in air and is observed to displace 0.015 litre of water when immersed in it. Densities of gold and copper with respect to water are, respectively, 19.3 and 8.9.The approximate percentage of copper in the ornament is ______.

Answer 1

In air weight of ornament$=0.25Kg$

Volume in water when the ornament immersed in it

$V=0.015litre=0.015m^3$

Density of gold and copper with respect to water are $=19.3$ and $8.9$

As per question,

Let the weight of the copper cooper $=xkg$

$\therefore$ the weight of the gold $=(0.25-x)kg$

Now,

$\frac{x}{19.3}+\frac{0.25-x}{8.9}=0.0150.0518x+0.1123(0.25-x)=0.0150.0518x+0.02808-0.1123x=0.015-0.0605x=-0.01308x=0.216$

Now, The percentage of copper in the ornament $=\frac{0.216}{0.25}\times 100=86.4\%$