Question

: When we press the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to
A. Pressure of water
B. Gravity of the earth
C. Shape of rubber bulb
D. Atmospheric pressure

Answer 1

Hint: We are surrounded by air. It is due to a physical quantity, which is measured with an instrument called a barometer. This physical quantity is known as the atmospheric pressure which helps us to answer this question.

Complete answer:
Due to air pressure, the water in the dropper increases. The air in the tube and the bulb escapes in the form of bubbles when the bulb is squeezed. Because of this, pressure decreases inside the bulb. Atmospheric pressure on the liquid surface however is present. The water flows inside the tube as we release the bulb. Water passes from a higher pressure (water retained) to a lower pressure (glass tube inside).

Hence, the required answer is atmospheric pressure, option D.

Additional information:
Atmospheric pressure: The pressure within the Earth’s atmosphere is atmospheric pressure, also known as barometric pressure (after the barometer). The unit of pressure specified as \[101,325\,{\text{Pa}}\] (\[{\text{1,013}}{\text{.25}}\,{\text{hPa}}\];\[{\text{1,013}}{\text{.25}}\,{\text{mbar}}\] ) is the normal atmosphere (symbol: atm), which is equal to \[{\text{760}}\,{\text{mm}}\,{\text{Hg}}\], \[{\text{29,9212}}\,{\text{inches}}\,{\text{Hg}}\] or \[{\text{14,696}}\,{\text{psi}}\] . The atm unit is approximately equal to the mean ambient pressure of the sea level on Earth, i.e. the atmospheric pressure of the Earth at sea level is around \[{\text{1}}\,{\text{atm}}\].

Note: There are significant effects of barometric pressure on water chemistry and weather conditions. The amount of gas that can dissolve in water is affected by it. Sunny, clear, and favorable weather conditions are accompanied by high barometric pressure, but lower levels allow rainy and gloomy weather conditions.