Answer:

Explanation:
We are asked to convert an amount in grams to moles. To do this, we use the molar mass. This is the number of grams in one mole of a substance. It is the same value numerically as the atomic mass on the Periodic Table, however the units are grams per mole, not atomic mass units.
Look up the molar masses for the individual elements.
- Sodium (Na): 22.9897693 g/mol
- Oxygen (O): 15.999 g/mol
Look back at the formula: Na₂O. Notice there is a subscript of 2 after sodium. This means there are 2 atoms of sodium in every molecule, so we have to multiply sodium's molar mass by 2 before adding oxygen's.
- Na₂O: 2(22.9897693 g/mol)+ 15.999 g/mol = 61.9785386 g/mol
Set up a ratio using the molar mass.

Multiply by the given number of grams.

Flip the ratio so the grams of sodium oxide can cancel each other out.




The original measurement of grams given has 3 significant figures, so our answer must have the same. For the number we calculated, that is the hundredth place.
The 4 in the thousandth place tells us to leave the 8.

There are <u>2.48 moles of sodium oxide</u> in 154 grams, so choice A is correct.
The correct matches are:
1. Exosphere - Temperatures reach as high as 2000 C yet it feels very cold
This is the top layer of the atmosphere. The atoms are so dispersed that despite it having very high temperature it doesn't feel like it at all.
2. Thermosphere - Particles that have enough energy can escape into space
The thermosphere is the fourth highest layer of the atmosphere. The atoms in this layer are relatively distant from one another, so the particles that have enough energy manage to escape easily into the exosphere and then the space.
3. Mesosphere - It is the coldest region of the atmosphere
The mesosphere is the third highest layer. In this layer the temperatures constantly drop, and they go down to -85 degrees, making it the coldest layer by far.
4. Stratosphere - Ninety percent ozone is in this layer
The startosphere has a separte zone in it which is dominated by only one gas, the ozone. It is called the ozone layer, the one that protects the Earth from too intense UV radiation, and in fact over 90% of this gas is locate here.
5. Troposphere - It is warm due to the heat from Earth's surface
The troposphere is the densest and lowest of the layers. It is the one that also has Greenhouse gases which manage to trap the heat that is radiated from the surface of the Earth, thus keeping this layer relatively warm.
Hey there!:
a) Cations which are lowest size generally forms adopts more number of water molecules around it. Such kind of Cations forms largest hydrated ions. Among given cations, Li+ is smallest one and (C4H9)4N+ is largest one. So, Li+ ion forms largest hydrated ion.
b) Organic ligands or alkyl chains contained Cations are hydrophobic in nature due to its low polar nature. Among given (C₄H₉)4N⁺ cation is hydrophobic in nature.
c) Size of cation inversely proportional to the hydrated sphere or number of water molecules attached. So, in the given Cations (C₄H₉)4N⁺ is largest cation which attaches fewest water molecules.
d) Charge on the cation makes it more electrostatic maker. But size is inversily proportional to electrostatic property. (C₄H₉)4N⁺ is electrostatic structure breaker.
e) Al⁺³ has highest charge. So it is most electrostatic structure maker.
Hope this helps!
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