Answer:
A
Explanation:
Remember the number of valence electrons represent the group number. As shown in figure, there is only one electron in the valence shell. Therefore, this element belongs to group 1 elements also called as Alkali metals.
Furthermore, the number of electrons in a neutral atom equals number of protons. Hence, there are 11 protons in this element.
Also, number of protons equal atomic number therefore, the atomic number of this element is 11. And, by checking periodic table, the element having atomic number 11 is Sodium (Na).
Answer:
The mole fractions:




Explanation:
The reaction described is:

The limiting reactant is the HBr (oxygen is in excess).
a) The mass (in moles) balance for this sistem:
(the 0.78 is because of the fractional conversion)

(the 1.25 is because of the oxygen excess)
There is only one degree of freedom in this sistem, you can either deffine the moles of HBr you have or the moles of Br2 you want to produce. The other variables are all linked by the equations above.
b) Base of calculation 100 mol of HBr:




The mole fractions:




Answer:
The pH of the resulting solution is 9.02.
Explanation:
The initial pH of the buffer solution can be found using the Henderson-Hasselbalch equation:

Now, the perchloric acid added will react with ammonia:

Also, the moles of ammonium chloride will increase in the same quantity according to the following reaction:
NH₃ + H₃O⁺ ⇄ NH₄⁺ + H₂O

Finally, we can calculate the pH of the resulting solution:

Therefore, the pH of the resulting solution is 9.02.
I hope it helps you!
Answer: because he has more protons than ca
Explanation: