Which one of the following instruments is used for measuring moisture content of air?
- A.Hydrometer
- B.Hygrometer
- C.Hypsometer
- D.Pycnometer
Correct answer
Explanation
The correct answer is B, Hygrometer. A hygrometer measures humidity, that is, the amount of water vapour or moisture in the air.
The name comes from the Greek "hygros", meaning wet. A common type used in weather stations is the wet-and-dry bulb hygrometer, or psychrometer: two thermometers stand side by side, one with its bulb wrapped in a wet cloth. Evaporation cools the wet bulb, and the gap between the two readings gives the relative humidity; the drier the air, the bigger the gap. Hair hygrometers, which use the stretching of human hair in moist air, and electronic sensors are also used. Relative humidity is the main figure in weather reports that tells how muggy the air feels.
Option A is wrong because a hydrometer measures the relative density (specific gravity) of liquids, such as milk or the acid in a battery. Option C is wrong because a hypsometer finds the height of a place from the boiling point of water there. Option D is wrong because a pycnometer is a small bottle used to measure the density of liquids or powders.
Exam tip: Hygro is moisture in air, hydro is density of liquids, hypso is height.
Practice Questions
View allBronze is an alloy of copper and
- A.nickel
- B.iron
- C.tin
- D.aluminium
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Bronze is an alloy of copper and tin, usually about 88 parts copper to 12 parts tin. Adding tin makes copper harder, stronger and easier to cast, and bronze also resists corrosion well.
Read the full explanation →Which one of the following elements is present in the green pigment of leaves?
- A.Magnesium
- B.Iron
- C.Calcium
- D.Copper
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The green pigment of leaves is chlorophyll, and a magnesium atom sits at the centre of every chlorophyll molecule.
Read the full explanation →Consider the following actions :
1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode
In how many of the above actions is the function of accelerometer required?
- A.Only one
- B.Only two
- C.All three
- D.None
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An accelerometer measures acceleration, including the pull of gravity, and each of the three actions depends on reading it. An accelerometer is a small sensor, today usually a MEMS (micro-electro-mechanical system) chip, that senses changes in speed and the direction of gravity.
Read the full explanation →Consider the following statements :
1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
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Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.
Read the full explanation →Which one of the following cell organelles contains DNA?
- A.Golgi apparatus
- B.Mitochondrion
- C.Lysosome
- D.Endoplasmic reticulum
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Mitochondria carry their own small, circular DNA and their own ribosomes. Mitochondria are the powerhouses of the cell, where aerobic respiration makes ATP.
Read the full explanation →