Percent composition by mass of oxygen =
((16.0*6)/(40.1+2*(14.0+16.0*3)))*100%
= 58.5%
therefore, the answer is D
The elements are listed in order of increasing the atomic number. Its the number that is the number of protons in the nucleus of an atom.
Answer : The correct option is, (B)
Explanation :
Balance equation : Balanced equation are those equation in which the number of atoms of each element and the total charge must be same on products side and reactants side.
In the given options, only option (B) equation has correct formula and also a balanced equation.

while the other options has incorrect formulas and also an unbalanced equations.
The correct equation for option A is, 
The correct equation for option C is, 
The correct equation for option D is, 
Hence, the correct answer is, (B) 
The equilibrium constant, Kc=0.026
<h3>Further explanation</h3>
Given
1.72 moles of NOCI
1.16 moles of NOCI remained
2.50 L reaction chamber
Reaction
2NOCI(g) = 2NO(g) + Cl2(g).
Required
the equilibrium constant, Kc
Solution
ICE method
2NOCI(g) = 2NO(g) + Cl2(g).
I 1.72
C 0.56 0.56 0.28
E 1.16 0.56 0.28
Molarity at equilibrium :
NOCl :

NO :

Cl2 :

![\tt Kc=\dfrac{[NO]^2[Cl_2]}{[NOCl]^2}\\\\Kc=\dfrac{0.224^2\times 0.112}{0.464^2}=0.026](https://tex.z-dn.net/?f=%5Ctt%20Kc%3D%5Cdfrac%7B%5BNO%5D%5E2%5BCl_2%5D%7D%7B%5BNOCl%5D%5E2%7D%5C%5C%5C%5CKc%3D%5Cdfrac%7B0.224%5E2%5Ctimes%200.112%7D%7B0.464%5E2%7D%3D0.026)
Answer:
3.01 × 10^24 particles
Explanation:
According to Avagadro, in one mole of a substance, there are 6.02 × 10^23 atoms or particles.
Using the formula: N = n × NA
Where;
N= number of particles or atoms
n = number of moles
NA = Avagadro's constant or number
This means that for 5 moles of a substance, there will be:
5 × 6.02 × 10^23
= 30.1 × 10^23
= 3.01 × 10^24 particles