Answer:
Energy levels
Explanation:
Elements in one row of the periodic table have the same energy levels. A row on the periodic table is the horizontal arrangement of elements. These rows are called periods.
There are 7 periods on the periodic table.
- Each elements on a period begins with an atom having one valence electrons and then ending with completely filled orbitals.
- Elements in the same period are known to have the same electronic shells which is the energy level.
- The principal quantum number of their electrons is the same.
Answer:
There are seven significant figures
Explanation:
There are seven different digits within the number. Three 0s, one 2, one 8, and two 3s, adding up to seven different numbers. You exclude the first 0 when the number is a decimal, leaving seven significant figures. Hope this makes sense! :)
The second option only.
<h3>Explanation</h3>
A base neutralizes an acid when the two reacts to produce water and a salt.
Sulfuric acid H₂SO₄ is the acid here. There are more than one classes of bases that can neutralize H₂SO₄. Among the options, there are:
Metal hydroxides
Metal hydroxides react with sulfuric acid to produce water and the sulfate salt of the metal.
.
The formula for calcium sulfate
in option A is spelled incorrectly. Why? The charge on each calcium
is +2. The charge on each sulfate ion
is -2. Unlike
ions, it takes only one
ion to balance the charge on each
ion. As a result,
and
ions in calcium sulfate exist on a 1:1 ratio.
.
Ammonia, NH₃
Ammonia NH₃ can also act as a base and neutralize acids. NH₃ exists as NH₄OH in water:
.
The ion
acts like a metal cation. Similarly to the metal hydroxides, NH₃ (or NH₄OH) neutralizes H₂SO₄ to produce water and a salt:
.
The formula of the salt (NH₄)₂SO₄ in the fourth option spelled the ammonium ion incorrectly.
As part of the salt (NH₄)₂SO₄, the ammonium ion NH₄⁺ is one of the products of this reaction and can't neutralize H₂SO₄ any further.
<span>write out the balance equation
3NaOh+H3PO4->Na3PO4+3H2O
You are given everything needed to calculate
q=heat transfer=2.2*10^2,
H3PO4 moles= 1.5*10^-3,
NaOH moles=5.0*10^-3
equation is deltaHneutraliztion=q/Moles of limiting reagent
H3PO4 is limiting reagent because lowest moles, and is used up first
Now plug in variables
DeltaH=2.2*10^2(1.5*10^3)= 146.67kj/mole
Notice we had to convert J to kj,</span>