atomic mass=percentage of isotope a * mass of isotope a + percentage of isotope b * mass of isotope b+...+percentage of isotope n * mass of isotope n.
Data:
mass of isotope₁=267.8 u
percentage of isotope₁=90.3%
mass of isotope₂=270.9 u
percentage of isotope₂=9.7%
Therefore:
atomic mass=(0.903)(267.8 u)+(0.097)(270.9 u)=
=241.8234 u + 26.2773 u≈268.1 u
Answer: the mass atomic of this element would be 268.1 u
Resonance, leaving group, carbonyl carbon delta+, and steric effect is the most crucial variables that affect the relative reactivity of a functional group containing a carbonyl in an addition or substitution process.
Discussion:
1. Carbonyl Carbon Delta+: The carbonyl group becomes more electrophilic and accelerates nucleophilic assault when the carbonyl carbon delta+ is bigger.
2. Resonance: When the carbonyl is transformed into the tetrahedral adduct, it may be lost. Loss of resonance increases the energy of the transition state for this nucleophilic assault because resonance has the function of stabilizing. Therefore, a carbonyl functional group's resistance to nucleophilic attack increases as resonance in the group increases in importance.
3. Leaving group: Tetrahedral adduct fragmentation is encouraged by a better LG.
4. Steric effects: The nucleophilic attack on carbonyl carbon is delayed when sterically impeded.
Learn more about carbonyl here:
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Answer:
168°C is the melting point of your impure sample.
Explanation:
Melting point of pure camphor= T =179°C
Melting point of sample =
= ?
Depression in freezing point = 
Depression in freezing point is also given by formula:

= The freezing point depression constant
m = molality of the sample = 0.275 mol/kg
i = van't Hoff factor
We have:
= 40°C kg/mol
i = 1 ( non electrolyte)




168°C is the melting point of your impure sample.
The element cobalt can form compounds in two different oxidation states, +2 and +3.
The +2 state is more common.
The ion Co2+ (aq) is pink.
Other compounds of cobalt(II), which include both anhydrous Co2+ and complex ions, are commonly blue.
If an aqueous solution contains both cobalt(II) and chloride ions, the blue ion CoCl42- forms, in equilibrium with the pink Co2+ (aq) ion.
<span>CoCl42- (aq) <===========> Co2+ (aq) + 4Cl1-(aq)</span>