I got a different answer.
Answer: 1.93 x 10^24 molecules
Explanation:
CH4 is the chemical formula for methane, the first member of the alkane family.
Based on Avogadro's law:
1 mole of any substance has 6.02 x 10^23 molecule
So, 1 mole of CH4 = 6.02 x 10^23 molecules
3.2 moles of CH4 = Z
To get the value of Z, cross multiply:
(Z x 1 mole) = (6.02 x 10^23 molecule x 3.2 moles)
Z•mole = 19.26 x 10^23 molecules•mole
Divide both sides by 1 mole
Z•mole / 1 mole = 19.26 x 10^23 molecules•mole/ 1mole
Z = 19.26 x 10^23 molecules
Place Z in standard form
Z = 1.93 x 10^24 molecules
Thus, 3.2 moles of ch4 has 1.93 x 10^24 molecules
The correct answer is option E.
Explanation:
The pH of the solution is defined as negative logarithm of hydrogen ions concentration in a solution. Mathematically written as:
![pH=-\log[H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%5BH%5E%2B%5D)
The pOH of the solution is defined as negative logarithm of hydroxide ions concentration in a solution. Mathematically written as:
![pOH=-\log[OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%5BOH%5E-%5D)
The sum of ph and pOH is equal to 14.
pH + pOH = 14
A solution has a pH of 4.20.
![pOH=9.8=-\log[OH^-]](https://tex.z-dn.net/?f=pOH%3D9.8%3D-%5Clog%5BOH%5E-%5D)
![[OH^-]=1.58\times 10^{-10} M\approx 6.0\times 10^{-10} M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.58%5Ctimes%2010%5E%7B-10%7D%20M%5Capprox%206.0%5Ctimes%2010%5E%7B-10%7D%20M)
Hence, the correct answer is option E.
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
