1. What is average atomic mass of Lithium if 7.42 % exists as Li ( 6.015 g / mol ) and 92.58 % exists as ' Li ( 7.016 g / mol ) ? 2. Magnesium has three naturally occuring isotopes . 78.70 % of Magnesium atoms exist as Magnesium - 24 ( 23.9850 g / mol ) , 10.03 % exist as Magnesium - 25 ( 24.9858 g / mol ) and 11.17 % exist as Magnesium - 26 ( 25.9826 g / mol ) . What is the average atomic mass of Magnesium ? 3. Neon has two major isotopes , Neon - 20 and Neon - 22 . Out of every 250 neon atoms , 225 will be Neon - 20 ( 19.992 g / mol ) , and 25 will be Neon - 22 ( 21.991 g / mol ) . What is the average atomic mass of Neon ? 4. What is the atomic mass of Hafnium if out of every 200 atoms , 10 have mass 176.00 g / mol , 38 have mass 177.00 g / mol , 54 have mass 178.00 g / mol , 28 have mass 179.00 g / mol , and 70 have mass 180.00 g / mol ? 5. In a sample of 200 Chlorine atoms , it is found that 151 are CI ( 34.969 g / mol ) , and 49 are "
0 +5 +2 +1
4Cu+10HNO3(р)=4Cu(NO3)2+N2O+5H2O;
Сu(0)___-2eCu(+2) 2 4восст
4
N(+5)+4eN(+1) 4 2 окисл
0 +5 +2 0
5Cu+12HNO3(p)=5Cu(NO3)2+N2+6H2O;
Cu(0)_-_--2eCu(+2) 2 5 воссст
10
2N(+5)+10e_N2(0) 10 1 окисл
0 +5 +2 -3
4Cu+10HNO3(oч.р)=4Cu(NO3)2+NH4NO3+3H2O
Cu(0)___-2e_Cu(+2) 2 4 восст
6
N(+5)_+8eN(-3) 8 1 окисл