The law of conservation of energy is a statement that : energy must be conserved and you are breaking a law if you waste energy.
the total amount of energy is constant for a closed system.
the supply of energy is limited so we must conserve.
energy can be used faster than it is created.
energy cannot be used faster than it is created.

option  B

Explanation:

The correct answer is option  B

From the option given option B describes law of conservation of energy which is total amount of energy is constant for closed system.

law of conservation of energy stated that energy cannot be created nor be destroyed but it can transformed from one form to another.

rest options are not correct as they does not follow the statement of the energy conservation.

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.

the answer is a. at the equator