# Samacheer Kalvi 8th Science Book Back Answers Chapter 1

## Samacheer Kalvi 8th Science Book Back Question and Answers:

Samacheer Kalvi 8th Standard Science Book Back 1 Mark and 2 Mark Question & Answers PDF uploaded and available below. Class 8 New Syllabus 2022 to 2023 Book Back Questions & Answers/solutions available for both English and Tamil Medium. Class 8 std Science Book Chapter 1  – Measurement Answers/Solutions Guide are uploaded on this page. 8th standard Science Book is consists of 23 Units. All 23 chapters of Science Book Back One, and Two Mark Solutions are given below.

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### 8th Science Book Back Chapter 1 Solutions Guide PDF:

Samacheer Kalvi 8th Science Subject 1 Mark and 2 Mark Solutions Guide PDF available below. Click the Download option to download the book back 1 Mark & 2 Mark questions and answers. Take the printout and use it for exam purposes.

### Measurement – Book Back Answers

1. Which one the following system of units is the British System of unit?
(a) CGS
(b) MKS
(c) FPS
(d) SI
(c) FPS

2. Electric current belongs to …………… quantities
(a) Base
(b) Supplementary
(c) Derived
(d) professional
(a) Base

3. SI unit of temperature is
(a) Celsius
(b) Fahrenheit
(c) kelvin
(d) Ampere
(c) kelvin

4. Amount of substance is
(a) Directly proportional to the number of atoms
(b) Inversely proportional to the number of atoms
(c) Directly proportional to the square of number of atoms
(d) Inversely proportional to the square of number of atoms
(a) directly proportional to the number of atoms

5. Luminous intensity is the intensity of
(a) Laser light
(b) UV light
(c) Visible light
(d) IR light
(c) visible light

6. Which one of the following devices is used to measure electric current 7. SI unit stands for
(a) International system of units
(b) Integrated System of units
(c) International symbol of units
(d) Integrated symbol of units
(a) International system of units

8. Closeness of two or more measured values is called as
(a) Accuracy
(b) Precision
(c) Error
(d) Approximation
(b) Precision

9. Quantities other than base quantities are called as
(a) Supplementary quantities
(b) Derived quantities
(c) Professional quantities
(d) Energy quantities
(b) Derived quantities

10. Which of the following statements about approximation is wrong?
(a) Approximation gives accurate value.
(b) Approximation simplifies the calculation.
(c) Approximation is very useful when little information is available.
(d) Approximation gives the nearest value only.
(a) Approximation gives accurate value.

II. Fill in the blanks

1. The solid angle is measured in ……………
2. …………….. recognized the need of ‘Standard Units’ for physical quantities.
3. The coldness or hotness of a substance is expressed by ……………..
4. …………….. is used to measure electric current.
5. ……………… of substance, contains 6.023 x 10+23atoms or molecules.
6. Luminous Intensity is the amount of visible light, that is emitted in unit area per unit …………….
7. Quartz clock uses …………….. oscillations.
8. The uncertainty in measurement is called as …………….
9. ……………… is the closeness of the measured value to the original value.
10. The intersection of two straight lines gives us ……………….

2. Scientists
3. Temperature
4. Ammeter
5. One mole
6. Solid angle
7. Electronic
8. Error
9. Accuracy
10. plane angle

III. True or False

1. SI units are metric system of units.
True

2. Temperature is a measure of total kinetic energy of the particles in a system.
False
Correct statement:
Temperature is a measure of average kinetic energy of the particles in a system.

3. In thermometers, freezing point of water is taken as the Upper Fixed Point.
False
Correct statement:
In thermometers, boiling point of water is taken as the Upper Fixed Point.

4. One coulomb of charge flowing per minute is called ‘ampere’.
False
Correct statement:
One coulomb of charge flowing per second is called ‘ampere’.

5. Amount of substance gives the number of particles present in the substance.
True

6. Intensity of light from a candle is approximately equal to one ‘candela’.
True

7. Angle formed at the top of a cone is an example of ‘Plane Angle’.
True

8. Quartz clocks are used in GPS Devices.
False
Correct statement:
Atomic clocks are used in GPS Devices.

9. Candela is used to express electric field intensity.
False
Correct statement:
Candela is used to express luminous intensity.

10. The number 4.582 can be rounded off as 4.58.
True

IV. Match the following 1 – b: 2 – e: 3 – d: 4 – a: 5 – c

V. Consider the statements given below and choose the correct option.

Mark the correct choice as

(a) If both assertion and reason are true and reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) Assertion is true, but reason is false.
(d) Assertion is false, but reason is true.

1. Assertion : The SI system of units is the suitable system for measurements.
Reason : The SI unit of temperature is kelvin.
(b) Both assertion and reason are true but reason is not the correct explanation of the assertion
Correct explanation :
In SI system the units are precisely defined and have the same value everywhere.

2. Assertion : Electric current, amount of substance, Luminous Intensity are the fundamental physical quantities.
Reason : They are independent of each other.
(a) Both assertion and reason are true and reason is the correct explanation of the assertion

3. Assertion : The seconds hand of a clock is having least count of one second.
Reason : Least count is the maximum measurement that can be measured accurately by an instrument.
(c) Assertion is true, but reason is false
Correct explanation :
Least count is the minimum measurement that can be measured accurately by an instrument.

4. Assertion : Avogadro’s number is the number of atoms in one mole of substance.
Reason : Avogadro’s number is a constant.
(a) Both assertion and reason are true and reason is the correct explanation of the assertion

5. Assertion : Radian is the unit of solid angle.
Reason : One radian is the angle subtended at the centre of a circle by an arc of length equal to its radius.
(d) Assertion is false, but reason is true]
Correct explanation :
Radian is the unit of plane angle.

1. What is the unit of mass in FPS system?
Pound.

2. How many base quantities are included in SI system?
Seven.

3. Give the name of the instrument used for the measurement of temperature.
Thermometer.

4. What is the ‘Lower Fixed Point’ of the Fahrenheit scale?
32°F.

5. What is the SI unit of Luminous Intensity?
Candela (cd).

6. What is the value of Avogadro’s number?
6.023 x 1023.

7. What type of oscillations are used in atomic clocks?
Periodic vibrations.

8. Mention the types of clocks based on their display.
Analog clock and digital clock.

9. How many times will the ‘minute hand’ rotate in one hour?