bonsoir pouvez vous s'il vous plait m'aider à mon exercice c'est pour demain. On peut considérer la terre comme une sphère de rayon R=6400 Km. 1) Quelle est la période de rotation de la terre autour de son axe ? 2) Calculer la vitesse angulaire de rotation de la terre. 3) Calculer la vitesse linéaire VE à l’équateur(=0°). 4) Calculer la vitesse linéaire VM d’un point situé à MARRAKECH (=28°).

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.

where’s the list ? the question is incomplete

it would be c. predictability