Question

A goldsmith desires to test the purity of a gold ornament suspected to the mixed with copper. The ornament weighs 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

ANSWER
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
∴ the weight of the gold =(0.25−x)kg
Now,
19.3
x
​
+
8.9
0.25−x
​
=0.015
0.0518x+0.1123(0.25−x)=0.015
0.0518x+0.02808−0.1123x=0.015
−0.0605x=−0.01308
x=0.216
Now, The percentage of copper in the ornament =
0.25
0.216
​
×100
=86.4%