This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Surface Tension”.
1. The unit of surface tension in the CGS system is ____________
a) N/m
b) Kg/cm
c) Dynes/cm
d) Dynes/m
View Answer
Explanation: The unit of surface tension in CGS system is dynes/cm. It is N/m in S.I. system. Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible.
2. The apparatus used for the determination of surface tension of a liquid is ____________
a) Oedometer
b) Stalagmometer
c) Consolidometer
d) None of the mentioned
View Answer
Explanation: The apparatus used for the determination of surface tension of a liquid is called stalagmometer. It is equivalent to force per unit length.
3. Stalagmometer is cleaned to remove grease with the help of ____________
a) Chromic acid
b) Sulphuric acid
c) Distilled water
d) Tartaric acid
View Answer
Explanation: Stalagmometer is cleaned to remove grease with the help of chromic acid. It is used for the determination of surface tension.
4. The surface tension of water at 250C is ____________
a) 90.0 dynes/cm
b) 45.63 dynes/cm
c) 82.5 dynes/cm
d) 72.14 dynes/cm
View Answer
Explanation: The surface tension of water at 250C is 72.14 dynes/cm. It is a standard value.
5. On increasing the temperature, the kinetic energy of the liquid molecules ____________
a) Increases
b) Decreases
c) Remains constant
d) None of the mentioned
View Answer
Explanation: On increasing the temperature, the kinetic energy of the liquid molecules also increases. At high temperatures, randomness increases.
6. In case of water and glass, we get a concave meniscus because the adhesive force between water and glass are _______________ than the cohesive forces between water molecules.
a) Weaker
b) Stronger
c) Same
d) None of the mentioned
View Answer
Explanation: In the case of water and glass, we get a concave meniscus because the adhesive force between water and glass are stronger than the cohesive forces between water molecules.
7. Shapes of drops of liquid are spherical because of ____________
a) Viscosity
b) Conductivity
c) Absorption
d) Surface tension
View Answer
Explanation: Shapes of drops of liquid are spherical because of surface tension as it reduces the surface area to a minimum.
8. Select the incorrect statement from the following option.
a) In case of mercury and glass, we observe a convex meniscus
b) Surface tension is responsible for the rise and fall of the capillary tubes
c) If two drops encounter each other, they tend to repel each other
d) All of the mentioned
View Answer
Explanation: If two drops encounter each other, they tend to coalesce into a large drop. All the other options are correct. In the case of mercury and glass, we observe a convex meniscus and Surface tension is responsible for the rise and fall of the capillary tubes.
9. On increasing the temperature, the surface tension of the liquid ____________
a) Increases
b) Decreases
c) Remains constant
d) None of the mentioned
View Answer
Explanation: On increasing the temperature, the surface tension of the liquid decreases. It is inversely proportional to the temperature.
10. Which of the following is an application of surface tension?
a) Use of soaps and detergents as cleansing agents
b) Molecular structure can be elucidated by surface tension measurements through parachor values
c) Surfactants are incorporated in preparations like toothpaste
d) All of the mentioned
View Answer
Explanation: Use of soaps and detergents as cleansing agents, molecular structure can be elucidated by surface tension measurements through parachor values and surfactants are incorporated in preparations like toothpaste are the applications of surface tension.
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