hello ! please answer the 18 and the 19 questions
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Heya. !!
here is your answer :))
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18.
(a) Pressure is usually reported in units of pascal, atm and mm Hg
(b) Blood pressure is measured during the contraction of heart muscles (systolic blood pressure) and during the period of rest between the contractions (diastolic blood pressure).Thus it ha s two values.120 stands for systolic blood pressure and 80 stands for diastolic blood pressure.
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19.
EVAPORATION :- Change of liquid into vapours at any temperature below the boiling point.
● FOUR POINTS :-
1) More the humidity,less the amount of evaporation
2) More the temperature,more the amount of evaporation
3) More the surface area,more the amount of evaporation
4) More the wind speed,more the amount of evaporation
●DIFFER FROM BOILING :-
☆It is a slow process and takes a long time WHILE boiling is a fast process.
☆ It does not occur at fix temperature, it may occur at any temperature above melting point WHILE boiling occurs at a fixed temperature known as boiling point. For ex: 100 ˚C for water.
☆ It involves only surface of the substance only normal energy obtained from the environment WHILE boiling involves the entire bulk of the substance and needs heat energy to occur.
☆ No bubble is formed during evaporation WHILE boiling involves formation of bubbles.
● HOW DOES EVAPORATION CAUSES COOLING ?
=> Evaporation occurs when the particles of the liquid, absorb heat from the surrounding. The absorption of heat increases, the energy of the particles of the liquid, and they escape the liquid surface into gaseous form. Since, particle of liquid absorb heat from the surrounding, the amount of heat present in the surrounding decreases, which causes cooling in the surrounding.
______________
HOPE IT HELPS U :))
# Nikky
here is your answer :))
____________________
18.
(a) Pressure is usually reported in units of pascal, atm and mm Hg
(b) Blood pressure is measured during the contraction of heart muscles (systolic blood pressure) and during the period of rest between the contractions (diastolic blood pressure).Thus it ha s two values.120 stands for systolic blood pressure and 80 stands for diastolic blood pressure.
●●●●●●●●●●●
19.
EVAPORATION :- Change of liquid into vapours at any temperature below the boiling point.
● FOUR POINTS :-
1) More the humidity,less the amount of evaporation
2) More the temperature,more the amount of evaporation
3) More the surface area,more the amount of evaporation
4) More the wind speed,more the amount of evaporation
●DIFFER FROM BOILING :-
☆It is a slow process and takes a long time WHILE boiling is a fast process.
☆ It does not occur at fix temperature, it may occur at any temperature above melting point WHILE boiling occurs at a fixed temperature known as boiling point. For ex: 100 ˚C for water.
☆ It involves only surface of the substance only normal energy obtained from the environment WHILE boiling involves the entire bulk of the substance and needs heat energy to occur.
☆ No bubble is formed during evaporation WHILE boiling involves formation of bubbles.
● HOW DOES EVAPORATION CAUSES COOLING ?
=> Evaporation occurs when the particles of the liquid, absorb heat from the surrounding. The absorption of heat increases, the energy of the particles of the liquid, and they escape the liquid surface into gaseous form. Since, particle of liquid absorb heat from the surrounding, the amount of heat present in the surrounding decreases, which causes cooling in the surrounding.
______________
HOPE IT HELPS U :))
# Nikky
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