It isn't clear what you mean by "these clouds"; but in general, you would expect molecules to "survive" when the temperatures are not too hot.
Nebulas are interstellar clouds consisting of dust, hydrogen, helium and other ionized gases. Nebulas vary in size, so some are bigger than Earth, and others are not.
Green plants survive by taking in carbon dioxide, nutrients and water, and using sunlight to make carbohydrates and other complex molecules.
Clouds can change into other clouds as they move from different heights in the atmosphere. The temperature, wind and other air masses affect the clouds appearance and characteristics.
The interstellar medium is all the matter that exists between the stars in a galaxy. It mainly consists of gas (99%), with about 75% of this gas being in the form of molecular or atomic hydrogen, and about 25% in the form of helium. The other 1% is in the form of dust. The density of the interstellar medium is also very small: about 1 atom per cubic centimetre.There are two main types of interstellar mediums:Cold clouds of neutral atomic or molecular hydrogen, which are the raw materials wherein stars can be formed if it becomes gravitationally unstable and collapses.Hot ionized hydrogen near hot young stars.
Elements are cooked up inside the hot interiors of stars, and spread to interstellar clouds by means of supernova explosions, and when those clouds condense to form planets, different elements encounter each other and then form chemical bonds because those bonds allow them to have more stable electron configurations. These combinations of elements are then called chemicals.
No, other molecules need include but are not limited to: Nitrogen Calcium Potassium Sodium.....
With all due respect, an interstellar cloud is, by its definition, gas, plasma and/or dust (molecular particulates) in greater quantities than normally found in interstellar space. So, perhaps the answer is No, because there are other elements present.
It isn't completely clear what you mean with "interstellar aliens": aliens on planets surrounding other stars, or aliens capable of interstellar travel? In any case, it is currently unknown whether ANY life exists in other places of the Universe; whether it is aliens capable of interstellar travel, or even just bacteria on other planets. It seems likely, given the huge amount of planets in the Universe, that there is life somewhere else than Earth - but this hasn't been confirmed yet.
I believe it is "interstellar". Intergalactic is the space between galaxies. Deep space. Interstellar space is the space between stars, nebulas, and all other objects WITHIN a galaxy.
Tornadoes are produced by cumulonimbus clouds. Other clouds associated with tornadoes include wall clouds and funnel clouds.
As an interstellar gas cloud shrinks in size, it's gravitational potential energy gradually transforms into other forms of energy.
Molecules are not always equivalent to molecules, as some molecules have more atoms than other molecules, and other molecules have different kinds of atoms than other molecules.