We observe a glowing cloud of gas in space with a spectroscope. We note that many of the familiar lines of hydrogen that we know on Earth seem to be in a different place. They are shifted toward the blue or violet end of the spectrum compared to their positions in the spectrum of glowing hydrogen gas on Earth. From this we can conclude that: Group of answer choices the cloud is moving away from us the cloud is much hotter than hydrogen on Earth the cloud is moving toward us No information can be concluded from this observation alone the cloud is much cooler than hydrogen on Earth

No information can be concluded from this observation alone the cloud is much cooler than hydrogen on Earth

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.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.