Question

The density of liquid in which hydrometer sinks to the bottom of stem is X $gc{m}^{-3}$ . Find [X]. {Where , [] is a step function}

• A. 0
• B. 1
• C. 2
• D. 9

Answer 1

The correct option is B 1

Let the volume of hydrometer bulb be $V$.
When hydrometer sinks to the mark $5cm$ of the stem.
Using the law of flotation, we have
$(V+5)\times D_w\times g=200\times g$
Because, $D_w=1g/{cm}^3$.
$V=1{95cm}^3$.
When the hydrometer sinks to the bottom,
$195\times D_L\times g=200\times g$.
$D_L=\frac{200}{195}=1.0g/{cm}^3$.
Hence, the density of liquid in which hydrometer sinks to the top of stem is $1g/{cm}^3$ $=X$ .