﻿ A piece of brass (alloy of copper and zinc) weighs 12.9 g in air. When completely immersed in water it weighs 11.3 g. what is the mass of copper contained in the alloy? Specific gravities of copper and zinc are 8.9 and 7.1 respectively.     : Kaysons Education

# A Piece Of Brass (alloy Of Copper And Zinc) Weighs 12.9 G In Air. When Completely Immersed In Water It Weighs 11.3 G. What Is The Mass Of Copper Contained In The Alloy? Specific Gravities Of Copper And Zinc Are 8.9 And 7.1 Respectively.

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## Question

### Solution

Correct option is

7.61 g

If the alloy contains m g of copper, the amount of zinc in it will be (12.9 –mg. So the volumes of copper and zinc will be respectively

and hence, the total volume of alloy,

Now as the weight of alloy in air and water is 12.9 g and 11.3 g respectively,

Substituting V from eq. (2) in (i) and solving for m, we get

m = 7.61 g.

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