2. Calculate the number-average molecular weight of a random poly (isobutylene-isoprene) copolymer in which the fraction of isobutylene repeat units is 0.25; assume that this concentration corresponds to a degree of polymerization of 1500.

Answer : The number-average molecular weight is, 97500 g/mol

Explanation :

First we have to calculate the molecular weight of isobutylene and isoprene.

The molecular formula of isobutylene and isoprene is, and

Molecular weight of = 4(12 g//mol) + 8(1 g/mol) = 56 g/mol

Molecular weight of = 5(12 g//mol) + 8(1 g/mol) = 68 g/mol

Now we have to calculate the average repeat molecular weight.

Average repeat molecular weight =

Average repeat molecular weight = 65 g/mol

Now we have to calculate the number-average molecular weight.

Number-average molecular weight = Average repeat molecular weight × Degree of polymerization

Number-average molecular weight = (65 g/mol) × (1500)

Number-average molecular weight = 97500 g/mol

Thus, the number-average molecular weight is, 97500 g/mol

the answer is: they rebelled against saddam hussein’s rule.

kurds opposed saddam rule and wanted independence. kurds in the north and shiites in the south revolt against hussein.

for example, the halabja attack in 1988 conducted against the kurdish people by the iraqi regime under saddam hussein, where between 4000 people are killed and around 9000 are injured.