How to find acceleration and displacement from this graph

Explanation:

In a velocity vs time graph, the slope of the graph is the acceleration. The area below the graph is the displacement. This gives the following answers:

19)

positive acceleration in A,B

negative acceleration in D,E

20)

greatest magnitude of acceleration in B

21) the object is standing still at the beginning of A

22) the speed is not changing in C

23) the area below the graph in A is 25/2 = 12.5

24) The area below the graph in B is 25 + 50/2 = 50

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.