If you know the Table of elements you can see it on.
In descending order from top:
E
F
D
A
C
B
All you really need to do is remember the symbols of each, and you’ve got it.
The charge of an ion of calcium that loses two electrons is D.) +2
hope this helps you
The number of moles in monochloro pentaborane (9)
is 0.37056.
We know that ,
Number of moles = Given mass/ Molar mass
Given mass of monochloro pentaborane (9) is 20.1 g
The molar mass of monochloro pentaborane (9) is
= 
= 
= 54.241
Thus number of moles = 20.1/54.241
= 0.37056
To know more about mole concept
brainly.com/question/20483253
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