Why atomic mass is an average vàlue

There are different isotopes for different elements

Explanation:

The mass of each of the isotopes of an element are added with their percentage each then they are divided by 100

Example boron 11 is 80 % boron 10 is 20%

Total mass of boron 10 is 20*10

Total mass of boron 11 is 80*11

Atomic mass is (20*10)+(80*11)/100

Which is 10.8 and it is rounded off as 11 in the periodic table

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water pollution kills aquatic life. aquatic life includes algae and other plant life that use photosynthesis. photosynthesis takes   c02 out of the air.  

c02is a greenhouse gas.

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :