COMEDK · Chemistry · 23. d and f Block Elements
The product and its colour when MnO\(_2\) is fused with KOH in presence of O\(_2\):
- A K\(_2\)MnO\(_4\), Dark green
- B KMnO\(_4\), Purple
- C Mn\(_2\)O\(_3\), Brown
- D MnO\(_2\), Black
Answer & Solution
Correct Answer
(A) K\(_2\)MnO\(_4\), Dark green
Step-by-step Solution
Detailed explanation
When \(MnO_2\) is fused with \(KOH\) in the presence of an oxidizing agent like \(O_2\) or \(KNO_3\), it forms potassium manganate (\(K_2MnO_4\)). The chemical equation for the reaction is: \(2MnO_2 + 4KOH + O_2 \rightarrow 2K_2MnO_4 + 2H_2O\) The product \(K_2MnO_4\) (potassium…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Chemistry
- Choose the correct statement.COMEDK 2025 Medium
- In the presence of a catalyst at a given temperature of \(27^{\circ} \mathrm{C}\), the Activation energy of a specific reaction is reduced by \(100 \mathrm{~J} / \mathrm{mol}\). What is the ratio between the rate constants for the catalysed \((\mathrm{k}_2)\) and uncatalysed \((\mathrm{k}_1)\) reactions?COMEDK 2024 Medium
- The IUPAC name of \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\) isCOMEDK 2013 Easy
- Nuclear theory of the atom was put forward byCOMEDK 2016 Easy
- 50 ec of oxalic acid is oxidised by 25 cc of \(0.20 \mathrm{~N} \mathrm{KMnO}\). The mass of oxalic acid present in 500 ce of the solution isCOMEDK 2019 Medium
- The mass of hydrogen in gram required to completely saturate 1 mole of triolein isCOMEDK 2012 Medium
More PYQs from COMEDK
- A wire of uniform cross section and resistance 4 ohms is bent in the shape of square ABCD. Point A is connected to a point \(\mathrm{P}\) on DC by a wire AP of resistance \(1 \mathrm{ohm}\). When a potential difference is applied between \(\mathrm{A}\) and \(\mathrm{C}\), the points \(\mathrm{B}\) and \(\mathrm{P}\) are seen to be in same potential. What is the resistance of part \(\mathrm{DP}\) ?
COMEDK 2024 Medium - Three vertices are chosen randomly from the nine vertices of a regular 9 -sided polygon. The probability that they form the vertices of an isosceles triangle, isCOMEDK 2023 Easy
- Given :
\(
\begin{gathered}
\Delta \mathrm{H}^0 \mathrm{f}_{\text {of }} \mathrm{CO}_2(\mathrm{~g})=-393.5 \mathrm{~kJ} / \mathrm{mol} \\
\Delta \mathrm{H}^0{ }_{\mathrm{f}} \text { of } \mathrm{H}_2 \mathrm{O}(\mathrm{l})=-286 \mathrm{~kJ} / \mathrm{mol} \\
\Delta \mathrm{H}^0{ }_{\mathrm{f}} \text { of } \mathrm{C}_3 \mathrm{H}_6(\mathrm{~g})=+20.6 \mathrm{~kJ} / \mathrm{mol}
\end{gathered}
\)
\(\Delta \mathrm{H}^0\) isomerisation of Cyclopropane to Propene \(=-33 \mathrm{~kJ} / \mathrm{mol}\)
What is the standard enthalpy of combustion of Cyclopropane?COMEDK 2024 Medium - A \(50\ \Omega\) galvanometer is shunted by a resistance of \(S\Omega\). If 8% of total current passes through the galvanometer, the value of S is:COMEDK 2026 Medium
- The mass of oxygen gas which occupies \(5.6 \mathrm{~L}\) at STP would beCOMEDK 2015 Easy
- Which of the following molecules does not exhibit dipole moment?
(i) \(\mathrm{CCl}_4\)
(ii) \(\mathrm{CO}_2\)
(iii) \(\mathrm{NH}_3\)
(iv) \(\mathrm{CHCl}_3\)
(v) \(\mathrm{H}_2 \mathrm{O}\)
(vi) \(\mathrm{CH}_3-\mathrm{O}-\mathrm{CH}_3\)COMEDK 2022 Medium