Answer:
1.13moles
Explanation:
Given parameters:
Number of atoms = 6.777 x 10²³ atoms
Unknown:
Number of moles = ?
Solution:
A mole of a substance contains the avogadro's number of particles
6.02 x 10²³ particles = 1 mole
6.777 x 10²³ atoms will contain 
= 1.13moles
Answer:
D
Explanation:
because the rest don’t make any sense
Answer:
B. One element and one compound
Explanation:
O2 is a diatomic element: "are pure elements that form molecules consisting of two atoms bonded together"
*there are 7 types of diatomic elements
and...
C8H12O6 is a compound
Chemical Compound can be described as "a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds"
<span>number of moles= mass / molecular mass
mass=131.50g
molecular mass of Zn(NO3)2 =189.39 g/mol
number of moles = 131.50 g/189.39 g/mol =0.69433 mol</span>
Answer:
B and C
Explanation:
When we have to do a buffer solution we always have to choose the reaction that has the <u>pKa closer to the desired pH value</u>. When we find the pKa values we will obtain:
![pKa_1=-Log[6.9x10^-^3]=2.16](https://tex.z-dn.net/?f=pKa_1%3D-Log%5B6.9x10%5E-%5E3%5D%3D2.16)
![pKa_2=-Log[6.2x10^-^8]=7.20](https://tex.z-dn.net/?f=pKa_2%3D-Log%5B6.2x10%5E-%5E8%5D%3D7.20)
![pKa_3=-Log[4.8x10^-^13]=12.31](https://tex.z-dn.net/?f=pKa_3%3D-Log%5B4.8x10%5E-%5E13%5D%3D12.31)
The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which 
is the <u>acid</u> and 
is the <u>base</u>. Therefore the answer for the first question is B and the answer for the second question is C.
