Because things that are burnt have been changed into something else like moldy bread thats cooked.
It is chemical change because you cannot unburn something.
Answer:
see explanation below
Explanation:
First to all, this is a redox reaction, and the reaction taking place is the following:
2KMnO4 + 3H2SO4 + 5H2O2 -----> 2MnSO4 + K2SO4 + 8H2O + 5O2
According to this reaction, we can see that the mole ratio between the peroxide and the permangante is 5:2. Therefore, if the titration required 21.3 mL to reach the equivalence point, then, the moles would be:
MhVh = MpVp
h would be the hydrogen peroxide, and p the permanganate.
But like it was stated before, the mole ratio is 5:2 so:
5MhVh = 2MpVp
Replacing moles:
5nh = 2MpVp
Now, we just have to replace the given data:
nh = 2MpVp/5
nh = 2 * 1.68 * 0.0213 / 5
nh = 0.0143 moles
Now to get the mass, we just need the molecular mass of the peroxide:
MM = 2*1 + 2*16 = 34 g/mol
Finally the mass:
m = 0.0143 * 34
m = 0.4862 g
Answer:
D.
Explanation:
Translation:
A. make a barbecue
B. organize a picnic
C. swimming in the pool
D. to go skiing
Barbecue is usually a summer activity, so we eliminate that.
It would be too cold for a picnic!
It would be too cold to go swimming, and that's more of a summer thing!
Skiing is a snow activity, and since it is winter, it is likely to know.
Answer : The number of iron atoms present in each red blood cell are, 
Explanation :
First we have to calculate the moles of iron.
Now we have to calculate the number of iron atoms.
As, 1 mole of iron contains 
number of iron atoms
So, 0.0519 mole of iron contains 
number of iron atoms
Now we have to calculate the number of iron atoms are present in each red blood cell.
Number of iron atoms are present in each red blood cell = 
Number of iron atoms are present in each red blood cell = 
Number of iron atoms are present in each red blood cell =
Therefore, the number of iron atoms present in each red blood cell are,
