Answer:

Explanation:
Regardless of the type of gas, 1 mole at standard temperature and pressure (STP) occupies a volume of 22.4 liters. In this case the gas is helium (He).
We can set up a ratio.

Multiply by the given number of moles.

The moles of helium will cancel.


Multiply.

5.25 moles of helium gas at STP is 117.6 liters of helium.
Hello!
The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.
We have the following data:
mo (initial mass) = 20 g
m (final mass after time T) = 5 g
x (number of periods elapsed) = ?
P (Half-life) = ? (in minutes)
T (Elapsed time for sample reduction) = 8 minutes
Let's find the number of periods elapsed (x), let us see:






Now, let's find the half-life (P) of the radioactive sample, let's see:





I Hope this helps, greetings ... DexteR! =)
The alkali metals can't exist alone in nature because of incomplete outermost shell of alkali metals.
<h3>What are the properties of alkali metals?</h3>
The alkali metals have the high thermal and electrical conductivity. It has high lustre, ductility, and malleability as compared to other materials. Each alkali metal atom has one electron in its outermost shell which make more reactive.
So we can conclude that the alkali metals can't exist alone in nature because of incomplete outermost shell of alkali metals.
Learn more about metal here: brainly.com/question/25597694
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You got the questions correct
Density decreases that's why ice floats on water because it's less dense than water.