Answer:
physical change is the temporary change or riversible change here the physical properties r only changed
for example when water is cooled its get freezed Nd becomes ice similarly wen ice is heated again then it becomes water so here it's not changed permanently
I hope my ans is comprehensive
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The Correct Answer is <u>D.Infrared/</u> <em>INFARED has a lower frequency than visible light/</em>
Answer : The time passed in years is 20.7 years.
Explanation :
Half-life = 28.1 years
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the time passed.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = ?
a = initial amount of the reactant = 1.00 g
a - x = amount left after decay process = 0.600 g
Now put all the given values in above equation, we get


Therefore, the time passed in years is 20.7 years.