Answer:
Option B
Explanation:
Magnesium is an alkali earth metal and chlorine is a nonmetal. Due to this, and their differences in electronegativity, the elements form an ionic bond. Since magnesium has two valence electrons, it will give them up to two chlorine atoms (which has 7 valence electrons), which needs them to complete its octet. From this, magnesium forms a cation, and will have the ion formula Mg(2+). The two chlorine atoms form anions, and will have the ion formula Cl(1-).
Terms:
- Cation: a positively charged ion
- Anion: a negatively charge ion.
- Electronegativity: the tendency of an atom in a molecule to attract the shared pair of electrons towards itself.
Answer is: D. Na2SO4.
b(solution) = 0.500 mol ÷ 2.0 L.
b(solution) = 0.250 mol/L.
b(solution) = 0.250 m; molality of the solutions.
ΔT = Kf · b(solution) · i.
Kf - the freezing point depression constant.
i - Van 't Hoff factor.
Dissociation of sodium sulfate in water: Na₂SO₄(aq) → 2Na⁺(aq) + SO₄²⁻(aq).
Sodium sulfate dissociates on sodium cations and sulfate anion, sodium sulfate has approximately i = 3.
Sodium chloride (NaCl) and potassium iodide (KI) have Van 't Hoff factor approximately i = 2.
Carbon dioxide (CO₂) has covalent bonds (i = 1, do not dissociate on ions).
Because molality and the freezing point depression constant are constant, greatest freezing point lowering is solution with highest Van 't Hoff factor.
A electrochemical reaction is said to be spontaneous, if
Answer 1:
Consider reaction: <span>Ni^2+ (aq) + S^2- (aq) ----> + Ni (s) + S (s)
The cell representation of above reaction is given by;
</span>

Hence,

we know that,

and

Therefore,

= - 0.25 - (-0.47) = 0.22 v
Since,
is positive, hence cell reaction is spontaneous
.....................................................................................................................
Answer 2: Consider reaction: <span>Pb^2+ (aq) +H2 (g) ----> Pb (s) +2H^+ (aq)
</span>
The cell representation of above reaction is given by;

Hence,

we know that,

and

Therefore,

= - 0.126 - 0 = -0.126 v
Since,
is negative, hence cell reaction is non-spontaneous.....................................................................................................................
Answer 3:
Consider reaction: <span>2Ag^+ (aq) + Cr(s) ---> 2 Ag (s) +Cr^2+ (aq)
</span>
The cell representation of above reaction is given by;

Hence,

we know that,

and

Therefore,

= - 0.22 - (-0.913) = 0.693 v
Since,
is positive, hence cell reaction is spontaneous