Because the helium inside it is lighter than air , hence it rises up
The balloon from our breath contains carbon dioxide which is heavier than air so it doesn’t rise
<span>Carrier Gas, Flow Controller, Column, Detector, Recorder
</span>First we have a cylinder containing the
carrier gas. From there, the carrier gas goes to the flow controller, which determines
how much carrier gas we are entering into the column (it doesn’t let more gas
pass through). Then, the carrier gas enters the column, which is the most
important part of the device. The sample enters the column from another place:
the injector. Then, the sample and the carrier gas go together across the
column. The interactions between the sample and the column will determine how
fast each sample component goes through the column, and so: which component
gets out earlier. So, at the end, you will have isolated each substance. Then,
each one passes (alone) through the detector, which measures something about
the sample – this information will let you know which substance it is. Finally,
the recorder provides you with the information the detector has found.
Nowadays, the recorder is a computer. In the “stone age” they just used a rudimentary
printer.
Option 2: 12.0 L of 
at STP.
The standard pressure and temperature values are 1 atm and 273.15 K.
Using the ideal gas equation, number of moles of gas can be calculated which is as follows:
PV=nRT...... (1)
Here, P is pressure, V is volume, n is number of moles, R is gas constant and T is temperature.
Also, in 1 mole of any gas there are 
molecules of the gas. This is known as Avogadro's number and denoted by symbol 
Thus,
Equation (1) can be rewritten as follows:
On rearranging,
Here, all the other terms are constant except volume, thus, gas with volume equal to the volume of 
will have same number of molecules.
Volume of gas and 
gas is same thus, will have same total number of molecules as gas.
Answer:
Option D
Explanation:
Rutherford deduced that the atomic nucleus was positively charged because the alpha particles that he fired at the metal foils were positively charged, and like charges repel. Alpha particles consist of two protons and two neutrons, so they are positively charged. In Rutherford's experiments most of the alpha particles passed straight through the foil without being deflected. However, occasionally the alpha particles were deflected in their paths, and rarely the alpha particles were deflected backward at a 180 degree angle.
Since like charges repel, Rutherford concluded that the cause of the deflections of the positively charged alpha particles had to be something within the atom that was also positively charged. Rutherford concluded from his metal foil experiments that most of an atom is empty space with a tiny, dense, positively charged nucleus at the center that contains most of the mass of the atom.
