At a location, rainwater runs off the face of a cliff that is 15 meters high. how is the face of the cliff likely to change over time? weathering by water would cut its middle deeper than the top. weathering by water would cut its top deeper than the middle. the top would slope gently due to deposition of sediments. colored mineral streaks would be formed due to erosion.

what best describes physical development during adolescence is the development of secondary sex characteristics happens at a rate unique to each individual.

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.