CBSE 10th Standard Science Subject Metals and Non-Metals Ncert Exemplar 5 Mark Questions 2021
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CBSE 10th Standard Science Subject Metals and Non-Metals Ncert Exemplar 5 Mark Questions 2021
10th Standard CBSE
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Reg.No. :
Science
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A non-metal A which is the largest costituent of air, when heated with H2 in 1 : 3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O2 it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.
(a) Identify A, B, C and D
(b) To which group of periodic table does this non - metal belong? -
Explain the following
(a) Reactivity of Al decreases if it is dipped in HNO3.
(b) Carbon cannot reduce the oxides of Na or Mg
(c) NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.
(d) Iron articles are galvanised
(e) Metals like Na, K, Ca and Mg are never found in their free state in nature. -
Of the three metals X, Y and Z, X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.
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An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.
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Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
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CBSE 10th Standard Science Subject Metals and Non-Metals Ncert Exemplar 5 Mark Questions 2021 Answer Keys
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Since the non-metal A is the largest costituent of air, it must be Nitrogen. When nitrogen is heated with hydrogen in the ratio of 1 : 3, it gives ammonia in presence of iron as a catalyst [Haber's process]. When nitrogen is heated with oxygen, it gives nitric oxide. When this oxide is passed through water in presence of air, it gives nitric acid which acts as a strong oxidising agent.
(a) A - N2; B - NH3; C - NO; D - HNO3
(b) Element A belongs to Group - 15 of the Periodic Table. -
(a) Due to the formation of a layer of oxide i.e., Al2O3
(b) Na or Mg is more reactive metals as compared to carbon.
(c) In solid NaCI, the movement of ions is not possible due to its rigid structure but in aqueous solution or molten state, the ions can move freely.
(d) To protect from corrosion.
(e) They are highly reactive. -
Since the metal X react with cold water, it must be high in the reactivity series i.e., sodium or potassium.
X is alkali metal, Na or K.
Since the metal Y reacts with hot water, it must be middle in the reactivity series i.e., magnesium or calcium.
Y is alkaline earth metal, Mg or Ca.
Since the metal X reacts with steam only, it must be low in the reactivity series i.e., iron Z is Fe.
Increasing reactivity series : Na > Mg > Fe. -
Since the element B belongs to atomic number 17, it must be chlorine.
The element which burns golden flame in air is sodium. Therefore, the element A must be sodium.
When element sodium and chlorine reacts, it forms sodium chloride, the compound C. The compound C on electrolysis gives sodium hydroxide and hydrogen gas.
Thus, A = Na; B = CI2; C = NaCI; D = NaOH.
Chemical Reactions involved:
\(2Na+{ CI }_{ 2 }\rightarrow 2NaCI\)
\(2NaCI(aq)+{ 2H }_{ 2 }O(I)\rightarrow 2NaOH(aq)+{ CI }_{ 2 }(g)+{ H }_{ 2 }(g)\) -
