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Science · 2024 · 3 marks
CBSE 2024 · Region 2 · Set 3 · Q27
(a)Sodium metal is stored under kerosene oil. Why ?(b)Some metal oxides are soluble in water. What are the aqueous solutions of these oxides called ? Write one example of such a solution.(c)At ordinary temperature the surface of metals such as magnesium, aluminium, zinc etc. is covered with a thin layer. What is the composition of this layer ? State its importance.
(a)
Sodium metal is stored under kerosene oil. Why ?
(b)
Some metal oxides are soluble in water. What are the aqueous solutions of these oxides called ? Write one example of such a solution.
(c)
At ordinary temperature the surface of metals such as magnesium, aluminium, zinc etc. is covered with a thin layer. What is the composition of this layer ? State its importance.
Marking-scheme solution
(a)
Sodium metal reacts vigorously and catches fires if kept in open.
(b)
Alkalis. e.g. NaOH/KOH
(c)
Composition of this layer is the respective metal oxide. It prevents the metal from further oxidation/ protects the metal.
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CBSE Class 10 Science past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.