Samacheer Kalvi 7th Science Term 2 Unit 1 Solutions

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Samacheer Kalvi 7th Science Term 2 Unit 1 Book Back Question and Answers/Solutions:

Samacheer Kalvi Class 7th Std Science Book Back 1 Mark and 2 Mark Question & Answers PDF uploaded and available below. Class 7th Standard New Syllabus 2022 to 2023 Book Back Question & Answer solutions available for both English and Tamil Medium. Class 7 New Science Book Term 2 Unit 1 – Heat and Temperature Answers/Solutions Guide are provided on this page. 7th Std Science Book is of 1st Term consists of 7 units, 2nd and 3rd Term consists of 6 units. All Units/Chapters of Term 1st, 2nd, 3rd Science Book Back One, and Two Mark Solutions are given below.

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Samacheer Kalvi 7th Science Book Back Chapter 1 Term 2 Answers/Solutions Guide PDF:

7th 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.

7th Science – Term 2 Chapter 1

Heat and Temperature

 

I. Choose the correct answer:

1. International unit of measuring temperature is
(a) Kelvin
(b) Fahrenheit
(c) Celsius
(d) Joule
Answer: (a) Kelvin

2. In thermometer when bulb comes in contact with hot object, liquid inside it
(a) expands
(b) contracts
(c) remains same
(d) none of above
Answer: (a) expands

3. The body temperature of a healthy man is;
(a) 0°C
(b) 37°C
(c) 98°C
(d) 100°C
Answer: (b) 37°C

4. Mercury is often used in laboratory thermometers because it
(a) is a harmless liquid
(b) is silvery in colour and is attractive in appearance
(c) Expands uniformly
(d) is a low cost liquid
Answer: (c) Expands uniformly

5. Which of the following temperature conversions is incorrect K (Kelvin) = oc ( Celsius) + 273.15
°C               K
a.       -273.15          0
b.      -123.         +150.15
c.      + 127.       + 400.15
d.     + 450        + 733.15
Answers: (d.)  °C + 450 ,k  + 733.15

II. Fill In the blanks:

  1. Doctor uses ________ thermometer to measure the human body temperature.
  2. At room temperature mercury is in _______ state.
  3. Heat energy transfer from _______ to _______
  4. -7°C temperature is _______ than 0°C temperature.
  5. The common laboratory thermometer is a _______ thermometer.

Answer:

  1. clinical
  2. liquid
  3. hotter object, colder object
  4. less
  5. mercury




III. Match the following:

  1. Clinical thermometer – A form of energy
  2. Normal temperature of human body – 100°C
  3. Heat – 37°C
  4. Boiling point of water – o°c
  5. Melting point of water – Kink

Answer:

  1. Clinical thermometer – Kink
  2. Normal temperature of human body – 37°C
  3. Heat – A form of energy
  4. Boiling point of water – 100°C
  5. Melting point of water – 0°C

IV. Give very short answer:

1. Temperature of Srinagar (J&K) is -4°C and in Kodaikanalis 3°C which of them has greater temperature ? What is the difference between the temperatures of these two places?
Answer:
Kodaikanal has greater temperature.
Temperature of srinagar (J &K) = -4°C
Temperature of = 3°C
Difference = -4°C + 3°C = 7°C
Srinagar is colder than that of kodaikanal.

2. Jyothi was prepared to measure the temperature of hot water with a clinical thermometer. Is it right or wrong? Why?
Answer:
It is wrong, because clinical thermometer has small temperature range (35°C to 42°C or 94°F to 108°F). If it is used to measure the temperature of hot water, the glass will crack/ burst due to excessive pressure created by expansion of mercury.

3. A clinical thermometer is not used to measure the temperature of air, why?
Answer:
The range of the clinical thermometer is less than that of thermometer used to measure temperature of air.

4. What is the use of kink in clinical thermometer?
Answer:
A kink is clinical thermometer prevents the mercury from flowing back into the bulb when the thermometer is taken out of the patient’s mouth, so that the temperature can be noted conveniently.

5. Why do we jerk a clinical thermometer before we measure the body temperature?
Answer:
The jerk to the thermometer will allow the mercury level to flow into the bulb so that the mercury level is below the normal temperature.

V. Give Short Answer:

1. Why do we use mercury in thermometers? Can water be used instead of mercury? What are the problems in using it?
Answer:

  1. We use mercury in thermometers as they remain in liquid form even with a change of temperature in it.
  2. A small change in the temperature causes change in volume of a liquid.
  3. Water cannot be used as a thermometric liquid, because it is not helpful to measure below 0°C and above 100°C.
  4. Water is transparent. So it makes the reading of the scales of the thermometer more difficult, water wets the glass tube so its steady is glass tube.
  5. Due to this constraints it is not used as a thermometric liquid.

2. Swathi kept a laboratory thermometer in hot water for some time and took it out to read the temperature. Ramani said it was a wrong way of measuring temperature. Do you agree with Ramani ? Explain your answer.
Answer:
Yes, I agree with Ramani.

  1. Laboratory thermometer does not have a kink. So, when Swathi takes out the thermometer, the level can go back because of absence of kink.
  2. So Swathi should note the reading when the thermometer bulb has surrounded by hot water.

3. The body temperature of Srinath is 99°F. Is he suffering from fever? If so, why?
Answer:
Srinath is having a fever because the normal body temperature is 98.6°F.

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