Answer:
Step-by-step explanation:
Water boils at 100 degree Celsius without vacuum.
With the addition of vacuum, the boiling temperature reduces to 83.5 degree Celsius.
The total reduction in boiling temperature is [tex]100 - 83.5 = 16.5[/tex] degree Celsius.
At first, the boiling temperature was 100 degree Celsius, which reduces by 16.5 degree Celsius.
The change in percentage is [tex]\frac{16.5}{100} \times100 = 16.5[/tex].