There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2Br2 molecules, and the mass of a Br2Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2Br2 consists of three peaks: Mass (amu)(amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 What is the origin of first (mass of 157.836 amu) peak (of what isotopes does each consist)

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 :

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the answer would be a

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.