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Answer:
c. F1-
Explanation:
In this chemical reaction the expression is:
HF + NaF → NaHF2
The ion that always keep the negative charge is the fluorine with a -1, if in this mixture there is more positive ions (H1+) the negative ion (F1-) will join with them.
Remember that also the Cl1- will be free, but the fluorine is more reactive than the fluorine.
Answer:
produce characteristic sets of energies, depending on the differences in energy between the excited states and ground state
Explanation:
The electron is jumped into higher level and back into lower level by absorbing and releasing the energy.
The process is called excitation and de-excitation.
Excitation:
When the energy is provided to the atom the electrons by absorbing the energy jump to the higher energy levels. This process is called excitation. The amount of energy absorbed by the electron is exactly equal to the energy difference of orbits. For example if electron jumped from K to L it must absorbed the energy which is equal the energy difference of these two level. The excited electron thus move back to lower energy level which is K by releasing the energy because electron can not stay longer in higher energy level and comes to ground state.
De-excitation:
When the excited electron fall back to the lower energy levels the energy is released in the form of radiations. this energy is exactly equal to the energy difference between the orbits. The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum
Answer:
Isotopes
Explanation:
We call atoms of the same elements with different mass numbers isotopes.
You have to find the number of moles of water and calcium sulfate.
to find the mass of water you subtract 3.87 by 4.89 to get 1.02g water and we are given taht the mass of calcium sulfate is 3.87g
then find the moles of water and calcium sulfate in the sample
1.02/18=0.05667mol water
3.87/136.2=0.0284 mol water
now you have to find how many moles there are per one mole of calcium sufate.
0.05667/0.0284=1.994 which can be rounded to 2 mol water for ever 1 mol calcium sulfate
therefore the formula for this CaSO₄·2H₂O and is called calcium sulfate dihydrate.
I hope this helps