The question is incomplete, here is the complete question:
At elevated temperature, nitrogen dioxide decomposes to nitrogen oxide and oxygen gas

The reaction is second order for
with a rate constant of
at 300°C. If the initial [NO₂] is 0.260 M, it will take ________ s for the concentration to drop to 0.150 M
a) 1.01 b) 5.19 c) 0.299 d) 0.0880 e) 3.34
<u>Answer:</u> The time taken is 5.19 seconds
<u>Explanation:</u>
The integrated rate law equation for second order reaction follows:
![k=\frac{1}{t}\left (\frac{1}{[A]}-\frac{1}{[A]_o}\right)](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B1%7D%7Bt%7D%5Cleft%20%28%5Cfrac%7B1%7D%7B%5BA%5D%7D-%5Cfrac%7B1%7D%7B%5BA%5D_o%7D%5Cright%29)
where,
k = rate constant = 
t = time taken = ?
[A] = concentration of substance after time 't' = 0.150 M
= Initial concentration = 0.260 M
Putting values in above equation, we get:

Hence, the time taken is 5.19 seconds
An increase in temperature will increase the average kinetic energy of the molecules. As the particles move faster, they will likely hit the edge of the container more often.
Answer and explanation;
Na - metal
Cl - poisonous gas
NaCl - cyrstaline solid that is edible
An emergent property is a property which a collection or complex system has, but which the individual members do not.
Water emergent properties: cohesion & adhesion, versatile solvent, temperature moderation, freezing.
The properties of a compound can be very different from the properties of the elements that make them, for example, Sodium is an explosive metal, and Chlorine is a toxic gas, however, sodium chloride is a Delicious table salt!
Answer:
It is neither a synthesis reaction nor a decomposition reaction because two reactants form two products.
Explanation:
This reaction would be considered a single replacement reaction.
Answer:
photons are emitted per second in a
Watt microwave oven.
Explanation:
The expression for the power is:-

Also, 
Where,
n = the number of photons
h = Plank's constant having value 
c = the speed of light having value 
= the wavelength of the light
So,

Thus, the expression for photons per second is:-

Given that:-
Power = 10³ Watt
( 1 cm = 0.01 m)
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So,

photons are emitted per second in a
Watt microwave oven.