The given reaction shows one of the processes to extract the metals like Iron and Manganese. MnO_2 (s) + Al (s) → Mn (l) + Al_2O_3 (s) + Heat (a) Give reason why the above reaction is known as a thermite reaction. (b) Identify the substance oxidised and reduced in the above reaction. (c) Give a reason why Aluminium is preferably used in thermite reactions.

ScienceCBSE Class 10 · Sample paper, session 2023-24 · 3 marks · Short answer

CBSE Class 10 Science sample paper 2023-24: question 27

From the official CBSE sample question paper for 2023-24, section C, question 27, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27 · 3 marks · Short answerMetals and Non-metals

The given reaction shows one of the processes to extract the metals like Iron and Manganese.

$Mn O_{2} (s) + Al (s) \to Mn (l) + A l_{2} O_{3} (s) + Heat$

(a)
Give reason why the above reaction is known as a thermite reaction.
1 mark
(b)
Identify the substance oxidised and reduced in the above reaction.
1 mark
(c)
Give a reason why Aluminium is preferably used in thermite reactions.
1 mark

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

Open one hint at a time and try again before the next.

Hint 1

Look at the 'Heat' and the state of Mn in the equation.

Hint 2

Oxidation is gain of oxygen; reduction is loss of oxygen. Then think about the reactivity series.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

Balanced equation: $3Mn O_{2} (s) + 4Al (s) \to 3Mn (l) + 2A l_{2} O_{3} (s) + Heat$
(a) The reaction is highly exothermic. So much heat is given out that the metal (Mn/Fe) is produced in the molten (liquid) state. That is why it is called a thermite reaction.
1 mark
(b) Al gains oxygen to form $A l_{2} O_{3}$ , so the substance oxidised is Al(s).
½ mark
$Mn O_{2}$ loses oxygen to form Mn, so the **substance reduced is $Mn O_{2}$ (s)**.
½ mark
(c) Aluminium is more reactive than Fe and Mn (it is placed above them in the reactivity series). It can therefore displace them from their oxides, acting as a strong reducing agent and releasing a lot of heat.
1 mark

Answer: (a) Highly exothermic reaction; the metal is obtained in molten state. (b) Oxidised: Al; Reduced: $Mn O_{2}$ . (c) Al is more reactive than Fe/Mn.

Where the marks are

Thermite because the reaction is highly exothermic / the metal forms in molten state (1 mark)
Al is the substance oxidised (0.5 mark)
$Mn O_{2}$ is the substance reduced (0.5 mark)
Al is above Fe/Mn in the reactivity series, i.e. more reactive (1 mark)

Revise the chapter

Chapter: Metals and Non-metals (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Metals and Non-metals, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2023-24: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.

CBSE Class 10 Science sample paper 2023-24: question 27

Hints

Step-by-step solution

Revise the chapter

More questions from Metals and Non-metals