You are designing a new home for a cold climate. You want one room in the house to be warmed by the Sun's energy. How will energy from the Sun warm that room? A. The ceiling will absorb the Sun's electromagnetic waves and keep them from entering the room.
B. Concrete flooring will transmit the Sun's electromagnetic waves away from the room.
C. The air in the room will absorb energy from the Sun's electromagnetic waves.
D. Glass will reflect the Sun's electromagnetic waves, preventing them from entering the room.​

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.

i'm on my way to history not a mistory.