Materials A, B, and C are solids that are at their melting temperatures. Material A requires 200 J to melt 4 kg, material B requires 300 J to melt 5 kg, and material C requires 300 J to melt 6 kg. Rank the materials according to their heats of fusion. If multiple materials rank equally, use the same rank for each, then exclude the intermediate ranking (i. e. if objects A, B, and C must be ranked, and A and B must both be ranked first, the ranking would be A:Greatest, B:Greatest, C:Third greatest). If all materials rank equally, rank each as 'Greatest'.

B: Greatest, A: Second greatest, C: Second geratest.

Explanation:

We can calculate the heat of fusion of a material (ΔHfus), which is the heat required to melt 1 kg of material, using the following expression.

ΔHfus = Q/m

where,

Material A

ΔHfus = 200 J/4 kg = 50 J/kg

Material B

ΔHfus = 300 J/5 kg = 60 J/kg

Material C

ΔHfus = 300 J/6 kg = 50 J/kg

Then, considering the heats of fusion,

B: Greatest, A: Second greatest, C: Second greatest.

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.