Physical Quantities and Measurement Class 6 ICSE Selina Questions and Answers

Class 6 • Measurement

Exercise 2
Measurement

Complete objective questions, short answers, long answers and numericals with animations, searchable content, answer reveals and a working unit-conversion lab.

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Length • Mass • Time • Temperature • Area

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ObjectiveShort answersLong answersNumericals

1

Objective Type Questions

Choose an option, check it instantly, and open the explanation when needed.

Question 1(a)Live MCQ

The symbol of degree Celsius is:

A°CB°FCKD°K

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Answer: °C

Reason: The symbol of degree Celsius is °C.

Question 1(b)Live MCQ

10 mm is equal to:

A1 cmB1 mC10 dmD10 cm

Show answer and reason

Answer: 1 cm

Reason: Since 1 m = 100 cm and 1 m = 1000 mm, we get 100 cm = 1000 mm. Therefore, 1 cm = 10 mm.

Question 1(c)Live MCQ

The amount of surface occupied by an object is called its:

AVolumeBAreaCMassDLength

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Answer: Area

Reason: The total surface occupied by an object is called its surface area, or simply area.

Question 1(d)Live MCQ

A metre ruler is graduated in:

AmBcmCmmDkm

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Answer: mm

Reason: A metre ruler is divided into centimetres, and each centimetre is divided into 10 millimetres. Its smallest division is normally 1 mm.

Question 1(e)Live MCQ

A thermometer is graduated in:

AKelvinB°CCgDcm

Show answer and reason

Answer: °C

Reason: Laboratory and clinical thermometers commonly show temperature on the Celsius scale.

Question 1(f)Live MCQ

Which one of the following units does not belong to the S.I. system?

AMetreBPoundCSecondDKilogram

Show answer and reason

Answer: Pound

Reason: In the S.I. system, metre is used for length, second for time and kilogram for mass. Pound is a unit of mass in the F.P.S. system.

Question 1(g)Live MCQ

1 square yard is equal to:

A1 yard × 1 yardB1 yard × 1 square footC1 yard × 1 acreDNone of these

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Answer: 1 yard × 1 yard

Reason: One square yard is the area of a square having each side equal to one yard.

Question 1(h)Live MCQ

1 acre is equal to:

A0.09290 m²B0.836 m²C4046.856 m²DNone of these

Show answer and reason

Answer: 4046.856 m²

Reason: 1 acre = 4046.856 m².

Question 2Fill in the blanks.View answer

(a) The S.I. unit of length is metre, of time is second, and of mass is kilogram.

(b) °C is the unit of temperature.

(c) 1 metric tonne = 1000 kg.

(d) The zero mark on a Celsius thermometer is the melting point of ice.

(e) The thermometer used to measure human body temperature is called a clinical thermometer.

(f) The commonly accepted normal human body temperature is 37°C or 98.6°F.

(g) The mass of an object is measured with a beam balance.

Question 3Write true or false for each statement.View answer

False(a) S.I. unit of temperature is Fahrenheit.
The S.I. unit is kelvin (K).

True(b) Every measurement involves a number and a unit.
Measurement = n × u = nu.

True(c) Mass is the measure of quantity of matter.

False(d) The S.I. unit of time is hour.
The S.I. unit is second (s).

True(e) Area can be expressed as the product of two length measurements.

Question 4Match the following columns.View answer

Column A	Correct match
Length of a housing plot	Measuring tape
Breadth of a book	Metre ruler
Mass of an apple	Beam balance
Period of time for study	Clock
Temperature of a body	Thermometer
Surface area of a leaf	Graph paper

2

Short Answer Type

Tap each question to reveal the complete answer.

Question 1What is measurement? How is a measurement expressed?View answer

Measurement is the comparison of an unknown quantity with a known fixed quantity of the same kind.

A measurement needs two things:

1. The unit, represented by u.
2. The number, represented by n, which tells us how many times the unit is contained in the quantity.

Measurement = n × u = nu

Question 2State two characteristics of a unit.View answer

A unit must have the following characteristics:

1. It should be of a convenient size.
2. It must be universally accepted. Its value must remain the same at all places and at all times.

Question 3Name four basic measurements in our daily life.View answer

LengthMassTimeTemperature

Question 4What are the S.I. units of mass, length, time and temperature? Write their names and symbols.View answer

Physical quantity	S.I. unit	Symbol
Length	metre	m
Mass	kilogram	kg
Time	second	s
Temperature	kelvin	K

Question 5Define one metre, the S.I. unit of length. State one multiple and one submultiple.View answer

One metre is defined as the distance travelled by light in 1/299,792,458 of a second.

Multiple: kilometre (km)

1 km = 1000 m

Submultiple: centimetre (cm)

1 cm = 1/100 m = 10⁻² m

Question 6The diagram shows a stick placed along a metre ruler. The length is observed with the eye at positions A, B and C.View answer

▧Mock image link: Parallax error diagramReplace this URL with your own direct image link.

(a) From position A, PQ = 3.4 cm. From position B, PQ = 3.2 cm. From position C, PQ = 3.0 cm. The readings are not the same.

(b) Position B is correct because the eye is vertically above the reading, which minimizes parallax error. The correct length of PQ is 3.2 cm.

Question 7Define mass. State its S.I., C.G.S. and F.P.S. units. How are they related?View answer

The mass of a body is the quantity of matter contained in it.

• S.I. unit: kilogram (kg)
• C.G.S. unit: gram (g)
• F.P.S. unit: pound (lb)

1 kg = 1000 g = 2.20462 lb

1 g = 10⁻³ kg ≈ 2.20462 × 10⁻³ lb

1 lb = 453.59 g = 0.45359 kg

Question 8Name the instrument commonly used to measure the mass of a body. State how it is used.View answer

A beam balance is commonly used to measure the mass of a body.

The body is placed on one pan and standard masses are placed on the other pan until the beam becomes horizontal. The total of the standard masses gives the mass of the body.

Question 9Define one kilogram, the S.I. unit of mass. How is it related to quintal, metric tonne and gram?View answer

For this level, one kilogram may be understood as approximately the mass of one litre of water near 4°C.

1 quintal = 100 kg

1 metric tonne = 1000 kg

1 gram = 10⁻³ kg

Question 10Name and define the S.I. unit of time. How is it related to minute, hour, day and year?View answer

The S.I. unit of time is the second (s).

1 minute = 60 seconds

1 hour = 3600 seconds

1 day = 86,400 seconds

1 year ≈ 3.15 × 10⁷ seconds

Question 11Name two devices used to measure a short time interval of an event.View answer

Stop clockStopwatch

Question 12What does temperature measure?View answer

Temperature measures the degree of hotness or coldness of an object.

Question 13Name the S.I. unit and one common unit of temperature. Write their symbols.View answer

S.I. unit: kelvin (K)

Common unit: degree Celsius (°C); degree Fahrenheit (°F) is also commonly used.

Question 14Write the temperature of melting ice and boiling water.View answer

❄Melting ice0°C

♨Boiling water100°C

Question 15What is the normal temperature of the human body? How is it indicated in a clinical thermometer?View answer

The normal temperature of the human body is commonly taken as 37°C or 98.6°F. In many textbook diagrams of a clinical thermometer, this value is indicated with a red arrow.

Question 16Can a clinical thermometer be used to measure the temperature of boiling water? Give a reason.View answer

No. A clinical thermometer cannot be used to measure boiling water at 100°C because its range is designed only for human body temperature, commonly about 35°C to 42°C.

Question 17Explain the term “area of a surface”.View answer

The total surface occupied by an object is called the area of its surface, or simply its area.

Question 18Name the S.I. unit of area and define it.View answer

The S.I. unit of area is the square metre, written as m².

One square metre is the area of a square whose side is one metre long.

Question 19How are square yard, hectare, km², cm² and mm² related to the S.I. unit of area?View answer

The S.I. unit of area is m².

1 square yard = 1 yard × 1 yard ≈ 0.836 m²

1 hectare = 10,000 m² = 10⁴ m²

1 km² = 1,000,000 m² = 10⁶ m²

1 cm² = 10⁻⁴ m²

1 mm² = 10⁻⁶ m²

3

Long Answer Type

Step-by-step explanations with clean mock image links ready for replacement.

Question 1How would you measure the length of a pencil using a metre ruler? What would you do if the ends of the ruler were broken?View answer

(a) Measuring with a normal ruler

1. Place the ruler with its markings close to the pencil.
2. Make the zero mark coincide with one end, P, of the pencil.
3. Read the position of the other end, Q, with the eye vertically above the mark to avoid parallax error.
4. The reading at Q gives the length PQ.

▧Mock image link: Pencil measured from zeroReplace with your own diagram URL.

(b) Measuring with a broken ruler

Place one end of the pencil at a clearly visible mark instead of zero. Read the positions of both ends. Subtract the smaller reading from the larger reading.

Length = final reading − initial reading

▧Mock image link: Pencil measured with a broken rulerReplace with your own diagram URL.

Question 2Name the instrument used for measuring the temperature of a person. Draw its neat labelled diagram.View answer

A clinical thermometer is used to measure a person’s body temperature.

▧Mock image link: Labelled clinical thermometerReplace with your own direct image link.

Question 3What is a clinical thermometer? State its special features and show its temperature range.View answer

A clinical thermometer is a special thermometer used for measuring a patient’s body temperature.

• It commonly has markings from 35°C to 42°C.
• It has a slight bend or kink in the stem just above the bulb, called a constriction.
• The constriction prevents the liquid column from falling back immediately.
• In many textbook diagrams, 37°C is marked to show the commonly accepted normal body temperature.

42°C40°C37°C35°C

▧Mock image link: Clinical thermometer range diagramReplace with your own direct image link.

Question 4Explain how you will measure the area of a square and a leaf.View answer

(a) Area of a square

The area of a regular shape can be found from its length measurements. Since all sides of a square are equal:

Area of a square = side × side = l × l = l²

(b) Approximate area of a leaf

The area of an irregular surface such as a leaf can be estimated using graph paper.

1. Place the leaf on graph paper.
2. Draw its outline and remove the leaf.
3. Count the complete squares inside the outline.
4. Add the incomplete squares that are half or more than half covered.
5. Ignore squares that are less than half covered.
6. Multiply the total count by the area of one square.

Approximate leaf area = (complete squares + half-or-more squares) × area of one square

▧Mock image link: Leaf traced on graph paperReplace with your own direct image link.

Question 5Which device would you use to measure the perimeter of a playground? Describe the procedure.View answer

A measuring tape is used to measure the perimeter of a playground.

1. Choose one corner as the starting point.
2. Place or secure the end of the tape at this point.
3. Stretch the tape straight and tightly along the first side.
4. Record the length and mark the endpoint.
5. Continue from that mark and measure the next side.
6. Repeat until all sides are measured.
7. Check alignment at every corner so no gap or extra length is included.
8. Add all side lengths to obtain the perimeter.

Perimeter = sum of the lengths of all sides

4

Numericals

Review the solved conversions and test values in the mini conversion lab.

Interactive Length Conversion Lab

MillimetreCentimetreMetreKilometreCentimetreMillimetreMetreKilometre

10 mm = 1 cm

Question 1Convert the following quantities as indicated.View answer

(a) 12 inch1 ft

(b) 1 ft30.48 cm

(c) 20 cm0.2 m

(d) 4.2 m420 cm

(e) 0.2 km200 m

(f) 0.2 cm2 mm

(g) 1 yard0.91 m approximately

Useful relations:

1 cm = 10⁻² m; 1 m = 100 cm; 1 km = 1000 m; 1 cm = 10 mm.

Question 2Express the given time intervals in seconds.View answer

(i) 3 minutes 15 seconds

3 × 60 + 15 = 180 + 15 = 195 seconds

(ii) 5 hours 2 minutes 5 seconds

5 × 3600 + 2 × 60 + 5 = 18,000 + 120 + 5 = 18,125 seconds

Question 3Convert the following mass quantities as indicated.View answer

(a) 2500 kg2.5 metric tonnes

(b) 150 kg1.5 quintals

(c) 10 lb4.5359 kg

(d) 2500 g2.5 kg

(e) 0.01 kg10 g

(f) 5 mg5 × 10⁻⁶ kg

Useful relations:

1 metric tonne = 1000 kg; 1 quintal = 100 kg; 1 lb = 0.45359 kg; 1 g = 10⁻³ kg; 1 mg = 10⁻⁶ kg.

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