Preparing 15 mg/gl working standard solution from a 20 mg/dl stock solution will require the application of the dilution principle.
Recalling the principle:
initial volume x initial molarity = final volume x final molarity
Since we were not given any volume to work with, we can as well just take an arbitrary volume to be prepared. Let's assume that the stock solution is 10 mL and we want to prepare 15 mg/gl from it:
Applying the dilution principle:
10 x 20 = final volume x 15
final volume = 200/15
= 13.33 mL
This means that in order to prepare 13.33 mL, 15 mg/l working standard solution from 10 ml, 20 mg/dl stock solution, 3.33 mL of the diluent must be added to the stock solution.
More on dilution principle can be found here: brainly.com/question/11493179
Some physical properties change, but the substance keeps its identity.
When dealing with these kind of questions, understand that the keyword here is physical change. Thus, all options that says no physical properties change are WRONG. So this leaves us with only 2 answers left. However, this is a physical change, no chemical change. Thus, the substance will keep its identity and not change.
Answer: orbitals supernumerary
Explanation:
Answer:
65.4 is the mass for 1.9×10²⁴ atomsof Pb
Explanation:
1mol of atoms of Pb has → NA (6.02×10²³ atoms) and weighs → 207.2 g
Therefore 1.9×10²⁴ atomsof Pb may weigh (1.9×10²⁴ . 207.2) / NA = 65.4 g
0.02375 moles
Explanation:
Fe2O3+CO :. Fe+CO2
We know that
56*2+16*3=160 gm of Fe2O3 can give 56 gm of Fe
So
3.8 gm can give 1.33 gm of Fe
It is equal to 1.33/56 moles of Fe which is equal to 0.02375 moles
