Answer:
the unknown substance is a protein
Explanation:
The biuret test is one of the tests for proteins. It can be used to detect peptide linkages. The biuret test is carried out in an alkaline solution. A coordination complex is formed leading to the appearance of a violet color.
Summarily, the biuret method is a colorimetric technique used to test for proteins and peptides. It involves the formation of a purple (violet) complex of Copper salts in alkaline solution.
Hence when the biuret reagent is added to an unknown substance and it turns purple, the unknown substance is a protein
Answer: 35.4 grams
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

where,
Molality = 2.65
n= moles of solute =?
= volume of solution in ml = 445 ml
Putting in the values we get:


Mass of solute in g=
Thus 35.4 grams of
is needed to prepare 445 ml of a 2.65 m solution of
.
A match-head is flammable, but you have to get it up to its ignition temperature first.
A diamond is flammable, but its ignition temperature is astronomical and
totally out of sight.
Answer : The value of diffusion coefficient is, 
Explanation :
Formula used :

where,
D = diffusion coefficient = ?
= 
= 
R = gas constant = 8.314 J/mol.K
T = temperature = 
Now put all the given values in the above formula, we get:


Thus, the value of diffusion coefficient is, 