Question

The apparent mass of a piece of metal when fully immersed in water is 60 gm. If the relative density of this metal piece is 2.5, find its actual mass (in gm)?
1. 300
2. 40
3. 400
4. 100

Answer 1

Correct Answer - Option 4 : 100

The correct answer is 100.

Given:

Relative density= 2.5.

Apparent Mass=60 gm.

Calculation:

\(Relative\ density= {True\ Mass\over True\ Mass-Apparent\ Mass}\longrightarrow\)①

Take true mass= x.

Substitute in \(\longrightarrow\)①

Relative density=\(= {x\over x-60}\)

\({5\over2}= {x\over x-60}\)

\(5x-300=2x\)

\(3x=300\)

\(x=100\)

∴Actual mass/True mass= x= 100 gm.