Given,
The two isotopes of B are 10B and 11B
% abundance of 10B = 19.80
% abundance of 11B = 80.20
Average atomic mass of B
= 
= 
= 
= 
= 10.802
Therefore, the average atomic mass of B is 10.802 u
Answer:
See explanation
Explanation:
From the analysis we have in the question, we must look towards a first row transition metal ion having a d^6 configuration because it yields a paramagnetic complex having four unpaired electrons and a diamagnetic complex having no unpaired electrons.
We have two possible candidates in mind, Fe^2+ and Co^3+. However, Fe^2+ does not form as many coloured complexes as stated in the question so we have to eliminate that option.
We are now left with only Co^3+. Various ligands are going to cause these various colours of Co^3+ to appear in solution.
Hence, we can deduce from all these that the nature of ligands determines the colour of the complex . Don't forget that the colour of a complex arises from crystal field splitting.
Answer:
Nuclear transmutation
Explanation:
The process in which an element spontaneously transforms into another isotope of the same element, or into a different element is called nuclear transumutation. It occurs when the number of protons or neutrons in the nucleus of an atom is changed.
Answer:
Should be number 4, quartz.
Explanation:
Quartz is rougher than calcite, therefore it's able to scratch it.
Answer:
Usually give off heat energy
Explanation:
Exergonic reactions are the ones which are spontaneous. Spontaneous reactions are indicated by the negative change in the Gibbs free energy. In order to provide characteristics for an exergonic reaction, we need to define the Gibbs free energy in terms of the enthalpy change and the entropy change:
Here:
is the enthalpy change;
is the entropy change;
is the absolute temperature.
In order to achieve a negative value in the Gibbs free energy change, we should have:
This is true for all temperatures if:
The major term here is the change in enthalpy, notice that we wish the enthalpy change to be negative.
Negative enthalpy change corresponds to an exothermic reaction, the one which releases heat. This means exergonic reactions would usually give off heat.
