Samacheer Kalvi 7th Science Term 2 Solutions Chapter 1 Pdf
Tamilnadu Board Samacheer Kalvi 7th Science Term 2 Solutions Chapter 1: Tamilnadu State Board Solution Class 7 Science Term 2 Chapter 1 – Heat and Temperature.
Samacheer Kalvi 7th Science Term 2 Solutions Chapter 1: Overview
Heat and Temperature
Samacheer Kalvi 7th Science Term 2 Solutions Chapter 1 Pdf
I.) Choose the correct answer
1.) International unit of measuring temperature is ……………………..
Answer : a. Kelvin
Solution : Kelvin is the international unit of measuring temperature.
2.) In thermometer when bulb comes in contact with hot object, liquid inside it
c.) remains same
d.) none of above
Answer : a. expands
Solution : In thermometer when bulb comes in contact with hot object, liquid inside it expands.
3.) The body temperature of a healthy man is;
Answer : b. 37°C
Solution : The body temperature pf a healthy man is 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
c.) Expands uniformly
d.) is a low cost liquid
Answer : c. Expands uniformly
Solution : Mercury is often used in laboratory thermometers because it expands uniformly.
5.) Which of the following temperature conversions is incorrect
K ( Kelvin) = °C ( Celsius) + 273.15 °C K
a.) -273.15 0
b.) -123. +150.15
c.) + 127. + 400.15
d.) + 450 + 733.15
Answer : d. + 450 + 733.15
II.) Fill in the blanks
1.) Doctor uses _clinical thermometer___ thermometer to measure the human body temperature.
2.) At room temperature Mercury is in __liquid__ state.
3.) Heat energy transfer from __hotter object_ to __colder object__
4.) 7°C temperature is _less__ than 0°C temperature.
5.) The common laboratory thermometer is a __mercury __ thermometer.
III.) Match the following
|i] Clinical thermometer||kink|
|ii]Normal temperature pf human body||37°C|
|iii] Heat||A form of energy|
|iv] Boiling point of water||100°C|
|v]Melting point of water||0°C|
IV.) Give very short answer
1.) Temperature of Srinagar (J&K) is 4°C and in Kodaikanal is 3°C which of them has greater temperature ? What is the difference between the temperatures of these two places?
Answer : Temperature of Kodaikanal is greater than temperature of Srinagar.
Difference between the temperatures of these two places : – 4°C + 3°C = 7°C.
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. Clinical thermometer can measure short range of temperature eg body temperature whereas, Water get hot at high temperature . Instead of clinical thermometer she should use laboratory thermometer.
3.) A clinical thermometer is not used to measure the temperature of air, why?
Answer : Clinical thermometer is not used to measure the temperature of air because it can measure very short range of temperature (between 35°C and 42°C) whereas temperatures of air can vary upto wide range of temperature.
4.) What is the use of kink in clinical thermometer?
Answer : A kink that 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 : we Jerk clinical thermometer before measurement to bring the level of the mercury down and get accurate reading.
V.) Give short Answer
1.) Why do we use Mercury inthermometers? Can water be used instead of mercury? What are the problems in using it?
Answer : We use mercury in theremometers because Its expansion is uniform ,opaque and shining, does not stick to the sides of the glass tube and has a high boiling point (357°C) and a low freezing point (−39°C). Hence a wide range of temperatures can be measured .
No, water can not be used instead of mercury. Because water is transparent and it can give reading between 0°C to 100°C.
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 .Because laboratory thermometer does not have kink .
As soon as Swathi take out the thermometer mercury will start droping. Correct way to note reading is when the bulb has been surrounded by the hot water from all sides.
3.) The body temperature of Srinath is 99°F. Is he suffering from fever? If so, why?
Answer : Yes, Srinath is suffering from fever because the normal temperature of the human body is 98.6°F. Srinath has a temperature of 99 °F which is greater than normal human body temperature.
VI.) Give long answer
1.) Draw the diagram of a clinical thermometer and label its parts.
2.) State the similarities and differences between the laboratory thermometer and the clinical thermometer.
Answer : Similarities in clinical and laboratory thermometer are :
i] both measure temperature
ii] mercury is used in both of them
Differences between clinical and laboratory thermometer :
i] Clinical thermometer is scaled from 35°C to 42°C whereas Laboratory thermometer is generally scaled from 10°C to 110°C.
ii] In clinical thermometer Mercury level does not fall on its own, as there is a kink near the bulb to prevent the fall of mercury level. Whereas Mercury level falls on its own as no kink is present.
iii] In clinical thermometer to lower the mercury level jerks are given. Whereas in laboratory thermometer no need to give jerk to lower the mercury level.
iv] Clinical thermometer is used for taking the body temperature Whereas laboratory thermometer is used to take temperature in laboratory.
VII.) Higher Order Thinking questions
1.) What must be the temperature in Fahrenheit, so that it will be twice its value in Celsius?
Temperature in Fahrenheit = 2×Temperture in Celsius
F –32 /9 = C /5
Let T be the temperature in Celsius. Then,
2T be the temperature in Fahrenheit
2T –32/ 9 = T/5
2T –32 = 9T /5
2T –9T/ 5 = 32
T/5 = 32
2T = 2×160°C
2.) Go to a veterinary doctor (a doctor who treats animals). Discuss and find out the normal temperature of domestic animals and birds.
Answer : The normal temperature of domestic animals and birds are recorded as follows:
The normal temperature of Goat varies from 37 – 40°C.
The normal temperature of a dog is about 38.3°C.
The normal temperature of a pigeon (bird) is 40°C.
The normal temperature of a cat is 38°C.