TRUE OR FLASE 17. People commonly dream about misfortune and being pursued by someone.

18. In terms of who is in their dreams-men have men in their dreams more than
women.

19. Sexual dreams are 1 in every 25 for men.

20. The activation-synthesis theory on dreams says that the brain engages in random
neural activity.

21. REM rebound refers to when you get too much sleep and spend part of your day
in an altered state.

17.true

18.true  

19.true 100% true

20.false

21.true

Explanation:

im awake at 1:10 in the morning and realizing how much my life s.ucks send halp ;-;

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.