Answer:
By measuring it's Radical velocity using Doppler Phenomenon...
Explanation:
It is done by measuring the absorption spectrum produces by a star as a result of measuring Doppler's relative wavelength. The star with the lower speed must have lower absorption spectrum extent as compared to the faster one.
Increasing temperatures in a reaction increases the kinetic energy of the reactant molecules. This causes them to move fast and hence collide with a higher frequency. The higher the rate of collision between the molecules, the faster the reaction.
Answer:
3.91 minutes
Explanation:
Given that:
Biacetyl breakdown with a half life of 9.0 min after undergoing first-order reaction;
As we known that the half-life for first order is:

where;
k = constant
The formula can be re-written as:



Let the initial amount of butter flavor in the food be
= 100%
Also, the amount of butter flavor retained at 200°C
= 74%
The rate constant 
To determine how long can the food be heated at this temperature and retain 74% of its buttery flavor; we use the formula:


Substituting our values; we have:

t = 3.91 minutes
∵ The time needed for the food to be heated at this temperature and retain 74% of its buttery flavor is 3.91 minutes
It's not chemical because it would have to react to something to change so it is physical change because it is the same thing but it just smells I hope this helped