When a small amount of KMnO$$_4$$ is added to concentrated H$$_2$$SO$$_4$$, a green oily compound is obtained which is highly explosive in nature. Compound may be :

When a small amount of potassium permanganate (KMnO4) is added to concentrated sulfuric acid (H2SO4), a reaction occurs. Let us understand this reaction step by step.

Potassium permanganate reacts with concentrated sulfuric acid to form manganese heptoxide. The balanced chemical equation for this reaction is:

$$ 2KMnO_4 + 2H_2SO_4 \rightarrow Mn_2O_7 + 2KHSO_4 + H_2O $$

Let us verify the atom balance on both sides to ensure the equation is correct.

Left side (reactants):

• Potassium (K): 2 atoms (from 2KMnO4)
• Manganese (Mn): 2 atoms (from 2KMnO4)
• Oxygen (O): From 2KMnO4 → 2 × 4 = 8 oxygen atoms, and from 2H2SO4 → 2 × 4 = 8 oxygen atoms, so total oxygen = 8 + 8 = 16 atoms
• Hydrogen (H): From 2H2SO4 → 2 × 2 = 4 hydrogen atoms
• Sulfur (S): From 2H2SO4 → 2 sulfur atoms

Right side (products):

• Mn2O7: 2 manganese atoms and 7 oxygen atoms
• 2KHSO4: Potassium (K) → 2 atoms, Hydrogen (H) → 2 atoms, Sulfur (S) → 2 atoms, Oxygen (O) → 2 × 4 = 8 atoms (since each KHSO4 has 4 oxygen atoms)
• H2O: 2 hydrogen atoms and 1 oxygen atom
• Total right side: K = 2, Mn = 2, O = 7 (from Mn2O7) + 8 (from 2KHSO4) + 1 (from H2O) = 16, H = 2 (from 2KHSO4) + 2 (from H2O) = 4, S = 2

The atoms balance: K (2=2), Mn (2=2), O (16=16), H (4=4), S (2=2). So the equation is correct.

The product manganese heptoxide (Mn2O7) is a dark green oily liquid at room temperature. It is highly unstable and explosive, decomposing violently when disturbed or heated. This matches the description in the question: "a green oily compound" that is "highly explosive".

Now, let us examine the options:

• Option A: MnSO4 (manganese sulfate) is a pale pink solid, not oily or explosive.
• Option B: Mn2O7 (manganese heptoxide) is a green oily liquid and highly explosive, matching the description.
• Option C: MnO2 (manganese dioxide) is a black or brown solid, not oily or explosive in this context.
• Option D: Mn2O3 (manganese(III) oxide) is a black solid, not oily or explosive.

Therefore, the compound obtained is manganese heptoxide (Mn2O7).

Hence, the correct answer is Option B.