Final answer:
To convert the temperature in the question to SI units, use the Kelvin (K) scale by adding 273.15 to the degrees Celsius (°C) value.
Step-by-step explanation:
The temperature in the question is given in degrees Celsius (°C). To convert it to SI units, we need to use the Kelvin (K) scale.
The Kelvin scale is related to the Celsius scale by the equation K = °C + 273.15.
In this case, the initial temperature is 21 °C + 273.15 = 294.15 K, and the final temperature is 85 °C + 273.15 = 358.15 K.
So, the temperature in SI units is 294.15 K to 358.15 K.