What is the age of a sample if there are 6 grams of an element that have not decayed out an original 24 grams and has a half-life of 8yrs. a. 8yrs b. 50yrs c. 29yrs d. 16yrs

16 years is the age of a sample.

Explanation:

The equation used to calculate half life for first order kinetics:

where,  

k = rate constant 

= half life of the sample

t = time taken for decay process

= initial amount of the sample

[A] = amount left after decay process 

We are given:

= 24 grams

[A] = 6 grams

Putting values in above equation, we get:

Rate law expression for first order kinetics is given by the equation:

On substituting the values we get value of t:

t = 16.00 years

16 years is the age of a sample.

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

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