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Science · 2026 · 3 marks
CBSE 2026 · Region 2 · Set 1 · Q26
Attempt either (a) or (b) :(a)Write one example each of one metal that is so soft that it can be cut with a knife, and one non-metal that is a good conductor of electricity.(ii)Using the electronic configuration, explain how Mg atom combines with oxygen to form magnesium oxide by transfer of electrons. [Atomic number : $\displaystyle \mathrm{Mg}=12, \mathrm{O}=8$ ]Give reasons : $\displaystyle 3 \times 1=3$(i)Metal sulphides and carbonates should be converted to their metal oxides in the process of extraction of metals.(ii)Aluminium oxide is considered as an amphoteric oxide.(iii)Metals like $\displaystyle \mathrm{Na}, \mathrm{K}, \mathrm{Ca}$ and Mg are never found in their free state in nature.
Attempt either (a) or (b) :
(a)
Write one example each of one metal that is so soft that it can be cut with a knife, and one non-metal that is a good conductor of electricity.
(ii)
Using the electronic configuration, explain how Mg atom combines with oxygen to form magnesium oxide by transfer of electrons. [Atomic number : $\displaystyle \mathrm{Mg}=12, \mathrm{O}=8$ ]
Give reasons : $\displaystyle 3 \times 1=3$
(i)
Metal sulphides and carbonates should be converted to their metal oxides in the process of extraction of metals.
(ii)
Aluminium oxide is considered as an amphoteric oxide.
(iii)
Metals like $\displaystyle \mathrm{Na}, \mathrm{K}, \mathrm{Ca}$ and Mg are never found in their free state in nature.
Marking-scheme solution
(a) (i)
Lithium (Li) / Sodium (Na) / Potassium (K) (anyone)
Graphite
\(\displaystyle \underset{[2,8,2]}{\mathrm{Mg}} \longrightarrow \underset{[2,8]}{\mathrm{Mg}^{2+}}+2 e^{-}\)
\(\displaystyle \underset{[2,6]}{\mathrm{O}^{-}}+2 e^{-} \longrightarrow \underset{[2,8]}{\mathrm{O}^{2-}}\)
\(\displaystyle \mathrm{Mg}: \overbrace{x}^{\times \underset{\times}{\times} \times}\)
OR
(b) (i) It is easier to obtain metal from its metal oxide / It is easier to reduce metal oxide to metal.
(ii) Aluminium oxide can react with both acids as well as bases to form salt and water.
\[\begin{gathered}
/ \\
\mathrm{Al}_{2} \mathrm{O}_{3}+6 \mathrm{HCl} \rightarrow 2 \mathrm{AlCl}_{3}+3 \mathrm{H}_{2} \mathrm{O} \\
\mathrm{Al}_{2} \mathrm{O}_{3}+2 \mathrm{NaOH} \rightarrow 2 \mathrm{NaAlO}_{2}+\mathrm{H}_{2} \mathrm{O}
\end{gathered}
\]
(iii) As they are highly reactive metals so exist in combined state.
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CBSE Class 10 Science past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.