Exercise answers
A. Tick the correct answer:
1. Which of these is not a green-house gas?
a. Hydrogen
b. Methane
c. Carbon dioxide
Ans. a. Hydrogen
2. Which of these is a result of the upthrust or the upward push of water?
a. Surface tension
b. Buoyancy
c. Refraction
Ans. b. Buoyancy
3. What gas is usually filled inside an electric bulb?
a. Argon
b. Oxygen
c. Hydrogen
Ans. a. Argon
4. Quartz crystals that are normally used in the quartz clocks are chemically known as:
a. Sodium silicate
b. Sodium hydroxide
c. Silicon dioxide
Ans. c. Silicon dioxide
5. Which of these is used as a lubricant?
a. Diamond
b. Graphite
c. Silicon
Ans. b. Graphite
6. The gases used in different types of welding include Oxygen and:
a. Hydrogen
b. Nitrogen
c. Acetylene
Ans. a. Hydrogen
7. The property of a substance to absorb moisture from the air is called:
a. Efflorescence
b. Sulfurosis
c. Deliquescence
Ans. c. Deliquescence
8. When an iron nail gets rusted iron oxide is formed. What happens to the weight of the nail in the process?
a. It increases
b. It decreases
c. No change
Ans. a. It increases
B. Match the commonly used substances with their chemical names:
C. The international system of units (SI System) has prescribed some basic units for the measurement of various physical quantities. Read each statement given below and complete the name of the unit.
1. The basic unit for the measurement of temperature.
K _ _ V _ _
Ans. KELVIN
2. The basic unit for measuring the luminous intensity.
C _ _ D _ _ A
Ans. CANDELA
3. The basic unit for the measurement of electric current.
A _ _ E _ E
Ans. AMPERE
4. The basic unit for the measurement of pressure or strain.
P _ _ _ A _
Ans. PASCAL
5. The basic unit for measuring the amount of a substance.
M _ _ _
Ans. MASS
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