Answer:
They used atomic number instead of atomic mass to organize the elements. From an element's location in the periodic table, you can predict: ... The elements have similar properties.
Answer:

Explanation:
Hello,
In this case, we use the Avogadro's number to compute the molecules of C2F4 whose molar mass is 100 g/mol contained in a 485-kg sample as shown below:

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Answer:
dont know, will let uk in 2 mins
Explanation:
When frequency increases more wave crests pass a fixed point each second. That means the wavelength shortens. So, as frequency increases, wavelength decreases. The opposite is also true.... as frequency decreases, wavelength increases.
There are 30 protons and 39 neutrons in the nucleus.
This must me the isotope of an element with an atomic mass close to 69 u.
The only candidates are Zn and Ga.
Zn has a zinc-69 isotope with mass 68.926 u.
Ga has a gallium -69 isotope with mass 68.925 u.
The isotope is probably

.
It has 30 protons and 39 neutrons.