To the eye – taken by itself – Alpha Centauri A appears as the fourth-brightest star seen from Earth, just slightly outshone by Arcturus. However, the combined light of Alpha Centauri A and B is slightly greater than Arcturus, so in that sense it appears as the third-brightest star visible in Earth's sky.
Answer: noble gasses
Explanation: zoom on on the red section and look at the key for what red means.
The molarity of a hydrochloric acid solution : 0.32 M
<h3>Further explanation </h3>
Titration is a procedure for determining the concentration of a solution by reacting with another solution which is known to be concentrated (usually a standard solution).
Titrations can be distinguished including acid-base titration, depositional titration, and redox titration. An acid-base titration is the principle of neutralization of acids and bases is used.
Acid-base titration formula
Ma. Va. na = Mb. Vb. nb
Ma, Mb = acid base concentration
Va, Vb = acid base volume
na, nb = acid base valence
1 ⇒HCl (valence=1, HCl ⇒H⁺+Cl⁻, one H⁺)
2⇒Ca(OH)₂(valence=2, Ca(OH)₂⇒Ca²⁺+2OH⁻, two OH⁻)
M₂=0.1 M
V₂=48 ml=0.048 L
V₁=30 ml=0.03 L

Answer:
Explanation:
Given parameters:
number of moles magnesium = 6.80mol
number of moles of chlorine = 13.56mol
To find the complete chemical formula, we should obtain the formula of the compound.
Mg Cl
Number of
moles 6.8 13.56
Dividing
by the smallest 6.8/6.8 13.56/6.8
1 2
The formula of the compound is MgCl₂
This is an ionic compound in which Magnesium loses two electrons that would be gained by Cl atoms requiring just an electron each to complete their octet.
You have to calculate the oxidation estates of the atoms in each compound.
I will start with K2Cr2O7 because I believe that Cr is the best candidate to reduce its oxidation number in 3 units.
In K2Cr2O7:
- K has oxidation state of 1+, then K2 has a charge of 2* (1+) = 2+.
- O has oxidation state of 2*, then O7 has a charge of 7* (2-) = 14-.
That makes that Cr2 has charge of 14 - 2 = +12, so each Cr has +12/2 = +6 oxidation state.
In Cr2O3:
- O has oxidation state of 2-, then O3 has charge 3 * (2-) = - 6
- Then, Cr2 has charge 6+, and each Cr has charge 6+ / 2 = 3+.
So, we have seen that Cr reduced its oxidation state in 3 units, from 6+ to 3+.
Answer: Cr has a change in oxidation number of - 3.