Answer: 27 Hope it helps u
<u>Answer:</u> The fraction of atom's mass contributed by nucleus is 0.99
<u>Explanation:</u>
Nucleons are defined as the sub-atomic particles which are present in the nucleus of an atom. Nucleons are protons and neutrons.
The isotopic symbol of Helium-4 atom is 
Number of electrons = 2
Number of protons = 2
Number of neutrons = 4 - 2 = 2
We are given:
Mass of He-4 atom = 
Mass of 1 electron = 
Calculating the mass contributed by the nucleus = 
Mass of the nucleus of He-4 atom = 
To calculate the fraction of atom's mass contributed by the nucleus, we use the equation:

Putting values in above equation, we get:

Hence, the fraction of atom's mass contributed by nucleus is 0.99
I'm going to have to say A. My reason to that is because when you leave a cup of hot cocoa (assuming its hot), it gives off the heat (exothermic) the
<span>1. Blocks Ultra violet rays that can be harmful.
2. Provides Oxygen, so we can live.
3. It blocks meteors from hitting Earth's surface.
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