Low-grade uranium ore contains a fraction of a percent (by weight) of uranium; very high-grade ore (as is found in some deposits in Canada) can contain up to 20% uranium.
A) If energy is extracted from uranium by fission of 235U (0.72% of naturally occurring uranium), then how large a percentage of uranium in ore is necessary to make a tonne of uranium ore equivalent (in terms of energy) to a tonne of coal?

2.857 gm

Explanation:

Step 1: Energy from uranium fission

The ratio of energy reeled from uranium to coal= 2.5 million times=2.5*10⁶

step2: mass of uranium 235 required

To get the same energy that of 1 ton coal, the mass reuied will be = (1/2.5) * 10⁻⁶ ton=0.4 * 10⁻³ Kg

where we have taken 1 ton = about 1000Kg

step3: mass of uranium

mass of u-235 = 70% of natural Uranium=0.7 Mu

So Mu= (1/0.7 )* mass of U-235=(0.4 * 10⁻³ Kg)/0.7=0.571 gm

Step 4: Mass of ore

mass of Mu = 20% of ore=0.2 M

So, mass of ore= (1/0.2 )* mass of MU-=(0.571)/0.2 gm=2.857 gm

tbh i dont know ether