Question

Radioactivity in drinking alcohol is there because of

	a.	potassium-40 in the ground
	b.	uranium in the ground
	c.	cosmic rays making C-14
	d.	nuclear reactor leakage

Which kind of material is most difficult to obtain

	a.	U-238
	b.	Plutonium-239
	c.	U-235
	d.	Deuterium

After three half lives, the amount of radioactivity remaining is:

	a.	3/4
	b.	1/2
	c.	1/3
	d.	1/8

Which is used for dating human bones?

	a.	Plutonium (Pu-239)
	b.	Pottasium-40 (K-40)
	c.	Radiocarbon (C-14)
		Deuterium (H-2)

Answer 1

1.

Radioactivity in drinking alcohol is there because of cosmic rays making C-14.

Generally alcohol is ethyl alcohol

C2H5OH

so you can see there is carbon molecule

and there is constant bombardmemt of cosmic rays from outside earth into atmosphere which turn C-12 in the alcohol into C-14 which is radioactive in nature

making alcohol radioactive

2. D option

Out of those four

deuterium is the least stable because least binding energy per nucleon.

You may have seen that graph of binding energy per nucleon

and Deuterium is isotopes of Hydrogen which lies on the left corner of the graph

so it is least stable

thats why it would be most difficult to obtain

because it decays faster out of four.

3.

N = No (1/2)^n where N remaining amount n= number of half life No initial amount so if n = 3 N = No (1/2)^3 = No/8 so D option.

4. C option.

C- 14

our bone has carbon as a constituent

so C-12 converts into C-14 after a long period of time.

so we can use C-14 in dating of human bones

and there is always proportion of C-14 available

like 0.99 % in proporton

and half life of C-14 is around 5000 year

so thats why.