Planets reflect sunlight. Most planets are close enough to the sun that they can reflect its light and that is why you can see them. Some planets that are far from the sun do not light up because they have no light to reflect.
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Answer: 
atoms of hydrogen are there in
35.0 grams of hydrogen gas.
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
1 mole of hydrogen 
= 
atoms
17.5 mole of hydrogen = 
atoms
There are atoms of hydrogen are there in
35.0 grams of hydrogen gas.
Answer:
After 2 half-lives there will be 25% of the original isotope, and 75% of the decay product. After 3 half-lives there will be 12.5% of the original isotope, and 87.5% of the decay product. After 4 half-lives there will be 6.25% of the original isotope, and 93.75% of the decay product.
Explanation:
so you can see those fluorine atoms have really spread out around the central phosphorus atom. this gives us a trigonal bi-pyramidal molecular geometry for pf5.
There is no path of electrons around the nucleus. There are however things called orbitals where you are likely to find electrons.
