71. A hydrometer floats with half of its stem outside water surface. It is now placed in alcohol (R.D = 0.8). The hydrometer floats
1. With stem at the same position
2. With more stem inside the alcohol
3. With more stem outside alcohol
4. In lifted position
A Hydrometer is an instrument which is used to measure the specific gravity (or relative density) of liquids. A hydrometer is usually made of glass and consists of a cylindrical stem and a bulb weighted with mercury or lead shot to make it float upright. The liquid to be tested is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer is noted. Hydrometers usually contain a scale inside the stem, so that the specific gravity can be read directly.
Numerical solution-
The density of alcohol (800 kg/m3 ) is less than that of water. So hydrometer will dip more than earlier.
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