3. What mass of lead (Pb) is needed to absorb 54,000 calories of energy if its temperature is to increase only by 2.5°C? (c = 0.128 J/g°C)

706.05 kg

Explanation:

convert calories to joules:

54,000cal -> 225,936j

convert word problem to math:

225936j / (x*2.5C)=.128 j/gC

find x

x=706050 grams

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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