Answer:
22.5°C
Explanation:
Given height of Celsius thermometer is 20 cm.
As we know the limit of a Celsius thermometer is 100°C
It is given that total height of thermometer is 20 cm.
So, this limit that is 100°C should be equal to 20 cm.
[tex]20\ cm\ =\ 100[/tex]°C
[tex]1\ cm\ =\ \frac{100}{20}[/tex]°C
[tex]1\ cm\ =\ 5[/tex]°C
Now, we want to find the temperature when the level of mercury was 4.5 cm.
[tex]4.5\ cm\ =\ 5\times 4.5[/tex]°C
[tex]4.5\ cm\ =\ 22.5[/tex]°C
Hence, we have 22.5°C temperature in Celsius thermometer when height of mercury is 4.5 cm above the lower mark.
