The atomic mass of Boron in the periodic table is 10.81. However not a single atom has a mass of 10.81. Explain PLS HELP ME

Reducing agents  oxidized by the reaction 

The answer is  d.  hydrogen 

Sink to the bottom. addition of potassium nitrate past it’s dissolution capacity at a particular temperature will cause the extra to just sink to the bottom of the glass.however, if you were to raise the temperature of the solution prior to dissolving it, and then slowly decrease the temperature after the dissolution, you would create a “supersaturated” solution - a solution that has more solute dissolved into it than should be allowed. if you add any extra solute past this, the entire solution would “crystallize,” and this is how you get those cool videos on youtube.

Moles of co₂ = 2.35/44 = 0.0534 mole.from ideal gas equation pv=nrt,  t = 18+273k = 291 kelvin.∴px5 = 0.0534x0.0821x291∴p = 0.0534x0.0821x291/5 = 0.2551 atm.now, 1 atm = 760 mm of hg  ∴ 0.02551 atm = 0.02551 x 760 = 19.38 mm of hg