<span>дано:</span>
<span>D=1мм=10</span><span>^</span><span>-9м</span>
<span>М(Н2О)=0,018 кг/моль</span>
<span><span> </span></span><span>p</span><span>=1000кг/м3</span>
<span>Na=6,02*10^23</span><span>моль-1</span>
<span>N</span><span>-?</span>
<span>m</span><span>=</span><span>pV</span><span>, </span><span>V</span><span>=4пR3/3</span>
<span>N=m*Na/M=pVNa/M=p4</span><span>пR3</span><span>Na/3M=4p</span><span>п</span><span>D3Na/24M= p</span><span>п</span><span>D3Na/6M</span>
<span>N=</span><span>1000*3,14*10</span><span>^</span><span>-9</span><span>*6,02*10^23/(6*0,018)=1,75*10^19</span>