Can some one please explain? 1). Compared to the chemical oxidation of one atom of carbon, a nuclear fission reaction using one atom of uranium can yield about times the energy output.
A)5
B)50
C)5000
D)5,000,000

2). In a nuclear fusion reaction, the total mass numbers of the reactants may equal the total mass numbers of the products. How can it still be true that mass is lost in nuclear fusion reactions?
A)In a nuclear fusion reaction, the fused nucleus is initially stable but then decays and loses mass.
B)The mass number is just an estimated mass measurement that is not precise.
C)The mass number only represents the total number of nucleons, which may be conserved.
D)In a nuclear fusion reaction, the products have greater kinetic energy than the reactants.

3). Nuclear fission reactions generally require:
A) small atomic nuclei to join together
B) large atomic nuclei to join together
C)small atomic nuclei to split apart
D)large atomic nuclei to split apart

Explanation:

1 )  D)5,000,000

Compared to the chemical oxidation of one atom of carbon, a nuclear fission reaction using one atom of uranium can yield about 5000000 times the energy output.

Energy in fission reaction comes from the conversion of mass into energy . This process results into creation of enormous amount of energy . But in the oxidation reaction of carbon , bonds are broken and new bonds are formed in which energy is used and released . The net energy released is difference of energy evolved minus energy used up . This difference is not much . Hence in such chemical reaction , energy released is not much .

2 ) B)The mass number is just an estimated mass measurement that is not precise.

In such calculation , the mass number used is just an estimated mass number and not the precise mass of particles involved . Hence , due to lack of precision in calculation , mass number appears to be constant . But actually there is decrease in mass in both fission and fusion reaction .

3 )  D

In fission reaction , large atomic nuclei splits into smaller nuclei to attain stability .