Answer:
Option C:- that is equal to mass of an proton.
Explanation:
Protons and neutrons have approximately the same mass, about 1.67 × 10-24 grams, which scientists define as one atomic mass unit (amu) or one Dalton. While electron has mass of 9.31 ×10⁻¹⁹.
<u>Answer:</u> The solubility of oxygen at 682 torr is 
<u>Explanation:</u>
To calculate the molar solubility, we use the equation given by Henry's law, which is:

Or,

where,
are the initial concentration and partial pressure of oxygen gas
are the final concentration and partial pressure of oxygen gas
We are given:
Conversion factor used: 1 atm = 760 torr

Putting values in above equation, we get:

Hence, the solubility of oxygen gas at 628 torr is 
The orbitals closest to the nucleus is the orbital wih the lowest energy. This is according to the basic rules stating that the energy of the shells as its principal quantum number increases, also increases. Thus the answer in 1 is B. Valence electrons are found in the outermost electron shell, on the other hand.