Answer:

Explanation:
Hello!
In this case, when determining empirical formulas by knowing the by-mass percent, we first must assume the percentages as masses so we can compute the moles of each element:

Now, for the determination of the subscript of each element in the empirical formula, we divide the moles by the fewest moles (P or N):

Thus, the empirical formula is:

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Answer : The partial pressure of
is, 222.93 torr
Explanation :
Half-life = 2.81 hr = 168.6 min
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the partial pressure of 
The balanced chemical reaction is:

Initial pressure 760 0 0
At eqm. (760-2x) 4x x
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = time passed by the sample = 215 min
a = initial pressure of
= 760 torr
a - x = pressure of
at equilibrium = (760-2x) torr
Now put all the given values in above equation, we get:


The partial pressure of
= x = 222.93 torr
Modern ceramics have all properties which have traditional ceramics for example hardness, high resistance to chemicals, and heat and they are different from traditional ceramic because have superior magnetic are or electrical properties.
One example is classical ceramic which is an insulator but when is dopped with ZnO it becomes a good conductor at high voltages.
to know more about clay ceramics and high tech ceramics here
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Answer:
C
Explanation:
For electromagnetic waves frequency X wavelength = speed of light
f * 2.2 x 10^-11 = 3 x 10^8 m/s
f = 3 x 10^8 / 2.2 x 10^-11
= 1.36 x 10 ^19
= 1.4 x 10^19 with two significant digits
Isotopes are variants atoms of the same element, having same number of atomic(proton) number but different number of neutrons and mass number.
Considering iron-60
- The atomic number which also equals the number of protons for the element iron as can be seen on the periodic table is 26
- The name iron-60 also tells us that this particlar isotope's mass number is 60.
- The chemical symbol for Iron is Fe
Now expressing as an isotope iron-60 becomes ⁶⁰₂₆Fe ( very unstable )
Other stable isotopes of Iron include ⁵⁴₂₆Fe , ⁵⁶₂₆Fe, ⁵⁷₂₆Fe and ⁵⁸₂₆Fe
See more here: brainly.com/question/11236150