The half-life of Co-60 is 5.3 years. If the initial mass of the sample is 1000g, how much will remain after 26.5 years.

31.25

Explanation:

The half life is 5.3 years

This means that 1.2 of the orginal matter is left after every 5.3 years.

To find this, divide 26.5(total years) by 5.3(hald life)

This gets you 5.

This is how many times half life occurs, or how many times the total mass is split in half.

This can be though of 1/2^5th power

Or

1/32

Now, lets mutliply this by the 1000 total mass:

1000*1/32

=

31.25g

This is your answer!

Hope this helps!

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.