The incorrect statement among the following is
(a) VOSO4 is a reducing agent.
(b) Cr2O3 is an amphot

Q: Why is VOSO4 considered a reducing agent?

In $VOSO_4$, Vanadium is in the $+4$ oxidation state. Since Vanadium can exhibit a maximum oxidation state of $+5$, it can lose one more electron (undergo oxidation). Substances that undergo oxidation act as reducing agents.

Q: How do we know that RuO4 is an oxidizing agent?

In $RuO_4$, Ruthenium is in its highest possible oxidation state of $+8$. It cannot be oxidized any further. Therefore, it can only accept electrons (undergo reduction), making it a strong oxidizing agent.

Q: What exactly makes an oxide amphoteric?

An amphoteric oxide is one that can react with both acids and bases to produce salt and water. $Cr_2O_3$ is a prime example, as it dissolves in acids to form $Cr^{3+}$ salts and in strong bases to form chromite ($CrO_2^-$) ions.

Q: If ruby isn't colored by Cobalt, what gives it its red color?

Ruby is made of Aluminum Oxide ($Al_2O_3$). Its red color comes from trace amounts of Chromium ($Cr^{3+}$) ions that replace some of the Aluminum ions in the crystal lattice.

Q: Are there other gemstones colored by transition metals?

Yes! For example, Emerald is a variety of beryl colored green by trace amounts of Chromium and sometimes Vanadium. Sapphire is also $Al_2O_3$ but gets its blue color from Iron ($Fe^{2+}$) and Titanium ($Ti^{4+}$) impurities.

Question

The incorrect statement among the following is

Options:

(A) $	ext{VOSO}_4$ is a reducing agent.

(B) $	ext{Cr}_2	ext{O}_3$ is an amphoteric oxide.

(C) $	ext{RuO}_4$ is an oxidising agent.

(D) Red colour of ruby is due to the presence of $	ext{Co}^{3+}$.

Sigma Percentile · Accepted Answer

### Decoding the Properties of d-Block Compounds

In this problem, we are tasked with identifying the incorrect statement among four given options. This requires a solid understanding of the oxidation states, acidic/basic nature, and real-world applications of various d-block elements and their compounds. Let's break down each statement logically.

### Analyzing the Oxidation States

Let's start with the first statement: **$VOSO_4$ is a reducing agent.** 
To verify this, we need to find the oxidation state of Vanadium ($V$) in $VOSO_4$. Let the oxidation state of $V$ be $x$. The oxide ion ($O^{2-}$) has a charge of $-2$, and the sulfate ion ($SO_4^{2-}$) also has a charge of $-2$. 
Setting up the equation: 
$$x + (-2) + (-2) = 0$$
$$x = +4$$
Vanadium belongs to Group 5 of the periodic table, which means its maximum possible oxidation state is $+5$. Since it is currently in the $+4$ state, it has the potential to lose one more electron and get oxidized to $+5$. A substance that undergoes oxidation acts as a **reducing agent**. Therefore, the first statement is perfectly correct.

Next, let's look at the third statement: **$RuO_4$ is an oxidising agent.**
In Ruthenium tetroxide ($RuO_4$), let's calculate the oxidation state of Ruthenium ($Ru$).
$$x + 4(-2) = 0$$
$$x = +8$$
Ruthenium is in the $+8$ oxidation state, which is the highest possible oxidation state for any element in the periodic table! Because it cannot lose any more electrons (it cannot be oxidized further), it can only accept electrons and undergo reduction. A substance that readily undergoes reduction is a **strong oxidising agent**. Thus, the third statement is also correct.

### The Nature of Chromium Oxide

The second statement claims: **$Cr_2O_3$ is an amphoteric oxide.**
Chromium(III) oxide ($Cr_2O_3$) is indeed a classic example of an amphoteric oxide. This means it can react with both acids and bases. 
When it reacts with an acid, it forms chromium(III) salts:
$$Cr_2O_3 + 6HCl \rightarrow 2CrCl_3 + 3H_2O$$
When it reacts with a strong base, it forms chromite ions:
$$Cr_2O_3 + 2NaOH \rightarrow 2NaCrO_2 + H_2O$$
Because it exhibits both acidic and basic behaviors, the statement is correct.

### The Chemistry of Gemstones

Finally, we arrive at the fourth statement: **Red colour of ruby is due to the presence of $Co^{3+}$.**
This is where the trap lies! Gemstones like ruby and sapphire are primarily composed of corundum, which is crystalline aluminum oxide ($Al_2O_3$). In its pure form, corundum is colorless. However, when trace amounts of transition metal ions replace some of the $Al^{3+}$ ions in the crystal lattice, they impart brilliant colors.

In the case of **ruby**, the red color is specifically caused by the presence of **$Cr^{3+}$ ions**, not $Co^{3+}$ ions. The $Cr^{3+}$ ions absorb light in the green and blue regions of the visible spectrum and transmit red light, giving ruby its characteristic deep red hue.

Therefore, the statement claiming that $Co^{3+}$ is responsible for the red color of ruby is **incorrect**. This makes option (d) our final answer.

Animated Solution for Chemistry - d and f-Block Elements: The incorrect statement among the following is

Select Answer:

Visualized Solution

$Analyzing Option (a): VOSO_{4}$

$Analyzing Option (b): Cr_{2} O_{3}$

$Analyzing Option (c): RuO_{4}$

$Analyzing Option (d): Red colour of ruby$

$Conclusion$

The Sigma Insight: Characteristics of d-block Elements

Decoding the Properties of d-Block Compounds

Analyzing the Oxidation States

The Nature of Chromium Oxide

The Chemistry of Gemstones

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