An oxide of nitrogen contains 30.45 mass % N, if the molar mass is 90± 5 g/mol the molecular formula is N₂O₄.
<h3>What is molar mass?</h3>
The molar mass of a chemical compound is determined by dividing its mass by the quantity of that compound, expressed as the number of moles in the sample, measured in moles. A substance's molar mass is one of its properties. The compound's molar mass is an average over numerous samples, which frequently have different masses because of isotopes.
<h3>How to find the molecular formula?</h3>
The whole-number multiple is defined as follows.
Whole-number multiple = 
The empirical formula mass is shown below.
Mw of empirical formula = Mw of N+ 2 x (Mw of O)
= 14.01 g/mol + 2 x (16.00 g/mol)
= 46.01 g/mol
With the given molar mass or the molecular formula mass, we can get the whole-number multiple for the compound.
Whole-number multiple = 
≈ 2
Multiplying the subscripts of NO2 by 2, the molecular formula is N(1x2)O(2x2)= N2O4.
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1. a 2.b 3 a 4. c. 4.a 5. d 6.a. 2Na + Cl2 2NaC 7.c. 3 8.3 9.b
Seeing signs of a chemical reaction does not always mean that a reaction is happening. For example, a gas (water vapor) is given off when water boils. ... You can tell that it is a physical change because water vapor can condense to form liquid water. In a chemical change, a new substance must be produced.
About 75% of earth’s surface is covered by the ocean
The reason why a wave get taller as it gets closer to shore is that the shallow water at the bottom of the wave makes the wave length smaller. Option B
<h3>What is a wave?</h3>
A wave is a disturbance that occurs along a medium which transmits energy. Now we now that waves travel from place to place. The horizontal distance that is travelled by a wave is what we call the wavelength of the wave.
As the wave approaches the shore, the wave tends to slow down because it is dragged from beneath. In the process, the wave grows taller. Thus, the reason why a wave get taller as it gets closer to shore is that the shallow water at the bottom of the wave makes the wave length smaller. Option B
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