Number of Valence Elections of the elements in the group.
Water Solution
Because you are testing the water solutions pH
Explanation:
Given parameters:
Atomic number = 82
Mass number = 207
Unknown:
Number of protons = ?
Number of neutrons = ?
Number of electrons = ?
Solution:
An atom is made up of some particles:
Protons are the positively charged particles
Electrons are negatively charged
Neutrons carry no charge
The atom is made up of dense and massive nucleus consisting of protons and neutrons.
The outer space is occupied by the electrons
The mass number is the number of protons and neutrons in an atom
Atomic number is number of protons
Number of protons = Atomic number = 82
Since the atom is a neutral atom, the number of protons is the same as the number of electrons and this is 82
The number of neutrons is the difference between mass and atomic number:
neutrons = 207 - 82 = 125
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The energy would be 3.31*10-19J
Answer:
D. 3.3 x 10^24
Explanation:
In a number representing a measurement, the significant figure are those digits that have a meaningful contribution to specify the resolution of the measurement.
When a number is written in scientific notation, it is written as:
where
m is the base
n is the exponent
When a number is written in this form, the number of significant figures is the number of digits contained in .
In this problem, our number is initially written as
We see that here "m" contains 4 digits, so here we have 4 significant figures.
In order to reduce it to 2 significant figures, we have to rewrite 3.311 as 3.3, therefore the new number will be:
Which is option D.