Answer:
A = 8
B = 8
C = O ( Oxygen )
D = 26
E = 30
F = Fe (Iron)
Explanation:
1)To get "A" we use the following formula
mass number = number of protons + number of. neutrons
15 = number of protons + 7
15 - 7 = number of protons
8 = number of protons
A = 8
2)To find "B"
atomic number = number of protons
Atomic number = 8
B = 8
3)To find "C"
the atomic number is 8 so the element which
has 8 atomic number on periodic table is Oxygen.
C = oxygen
4) To get "D"
Number of protons = atomic number
number of protons = 26
D = 26
5)To get "E"
mass number = number of protons + number of. neutrons
56 = 26 + number of neutrons
56 - 26 = number of neutrons
number of neutrons = 30
E = 30
6) To find "F"
The atomic number is 26 so the element which has 26 atomic number on periodic table is Iron.
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Solution :
We know that :
and 
Then,
..................(1)
Where,
= amount of solvent (in kg)
= amount of solute (in kg)
= molar mass of solute (g/mole)
= molality of solution (mole/kg)
Given :
=
, 


= 0.250 kg,
= 24.3 g
Then putting this values in the equation is (1),


g/mole
So, the molar mass of the unknown compound is 158.49 g/mole.
In the compound Co2O3, cobalt has an oxidation number of 3, while oxygen's oxidation number is -2.
An oxidation number is a number assigned to an element in chemical combination that represents the number of electrons lost (or gained, if the number is negative) by an atom of that element in the compound.
Answer:
The answer to the question is true.
The answer will be option D