Question

An alloy of copper and zinc has a mass of 12.9 g and its volume is 1.7 cm3 . If the mass of copper is 4.5 g, find the density of zinc.

Answer 1

Answer:

Correct option is

B

7.61g

Weight of brass in air = 12.9 g

weight of brass in water = 11.3 g

Weight of water displaced by brass = 12.9-11.3 = 1.6 g

Relative density of copper = 8.9= density of substance/density of water

Density f water = 1 g/cc

So, density of copper = 8.9 g/cc= Mass/ Volume

So, density of zinc = 7.1 g/cc

Volume of alloy = 1.6cc

Mass of copper in the alloy = x

Volume of alloy= Volume of copper + Volume of zinc

1.6=

8.9

x

+

7.1

12.9−x

Solving the above equation, x= 7.61 g