The prefix milli means thousand so the correct conversion factor is 1000mg/g
Answer : The time taken for the reaction is, 28 s.
Explanation :
Expression for rate law for first order kinetics is given by :
![k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%5Clog%5Cfrac%7B%5BA_o%5D%7D%7B%5BA%5D%7D)
where,
k = rate constant = 0.0632
t = time taken for the process = ?
![[A_o]](https://tex.z-dn.net/?f=%5BA_o%5D)
= initial amount or concentration of the reactant = 1.28 M
![[A]](https://tex.z-dn.net/?f=%5BA%5D)
= amount or concentration left time 't' = 
Now put all the given values in above equation, we get:
Therefore, the time taken for the reaction is, 28 s.
Answer: Chemical change
Explanation:
Physical change is a change in which there is no rearrangement of atoms and thus no new substance is formed. There is only change in physical state of the substance. The change can be reversed using physical methods.
Chemical change is a change in which there is rearrangement of atoms and thus new substance is formed. There may or may not be a change in physical state. The change can only be reversed using chemical methods.
Thus when iron and sulfur are heated in a test tube, the chemical change occurs and thus lead to formation of new substances which could not be separated using magnet.
