Answer:
Air does, in fact, have weight, and here's a simple way you can prove it. You'll need two identical balloons, a string, and a dowel. Attach the uninflated balloons to either end of the dowel. Attach the string to the center of the dowel and then hang it from something.
Explanation:
By definition, a halo is a part of a galaxy wherein it mainly consists of scattered stars forming bulges having a significantly spherical structure. In addition, the galactic structure is commonly made up of old and metal-rich stars forming clouds of gas and dirt at the spirals of a galaxy.
Answer:
The part that completes the nuclear equation is:

Explanation:
<h2>A) Preliminar explanation</h2>
The <em>nuclear equation</em> represents a nuclear reaction: the change of the nucleus of an atom.
The given equation represents an actinium atom releasing an alpha particle.
This is the meaning of each part of the equation:
- Ac is the chemical symbol of actinium
- The superscript to the left of the chemical symbol is the mass number of the atom (number of protons plus number of neutrons). The mass number is 225.
- The subscript to the left of the chemical symbol is the atomic number of the atom (number of protons). The atomic number is 89.
is the symbol of the alpha particle. It is an atom of helium- The mass number is 4
- The atomic number is 2
<h2>B) Solution</h2>
To <em>complete the nuclear equation </em>you must do two balances: mass number balance and atomic number balance.
<u>i) Mass number balance</u>
- 225 = A + 4 ⇒ A = 225 - 4 = 221
<u>ii) Atomic number balance</u>
- 89 = Z + 2 ⇒ Z = 89 - 2 = 87
Therefore, the mass number of the unknown atom is 221, and the atomic number is 87.
From a periodic table, the element with atomic number 87 is francium, Fr.
Now, you have the chemical symbol, the atomic number, and the mass number of the unknown atom, which lets you to write the atom that completes the <em>nuclear equation</em>.

The result of a wave generator traveling faster than the speed of a wave is called as a boom. If the wave is a sound wave, it is called a sonic boom. However, if the wave is light, it is called as a luminal boom. Luminal bloom happens in some industries and is commonly called as the Cherenkov radiation.