This worksheet 27 contains questions based on Chapter 27 Metals and Non-Metals of NIOS Class 10 Science and Technology (212) along with complete and accurate
answers.
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This post explains the answers of questions given in the worksheet including
explanation, diagrams. These solutions will help you complete your assignments and TMA also.
Metals and Non-Metals Worksheet 27 Solution
Q1. A metal ‘X’ loses two electrons and a non-metal ‘Y’ gains one electron. Show the electron dot structure of compound formed between them. Is compound ionic or covalent? Does it have high melting point or low? Will it conduct electricity in solid state or in aqueous solution and why? Will it be soluble in water?
Answer
Formation of compound
Metal X loses 2 electrons and becomes X2+
Non- metals Y gains 1 electron and becomes Y–
So, two Y atoms are required to accept 2 electrons from one X atom. Therefore, the
formula of compound is XY2.
Electron dot structure of compound
Type of compound
The compound formed is ionic or electrovalent. Because metal lose electrons to form
positive ions and non-metal gain electrons to form negative ions. So, bond is formed by transfer of electrons therefore it is an ionic compound.
Melting point of the compound
Ionic compounds have high melting point because there is strong electrostatic force
of attraction between oppositely charged ions.
Electrical conductivity
Ionic compounds do not conduct electricity in solid state because ions cannot move in
solid crystal lattice. Ionic compounds conduct electricity in aqueous solution or in molten state, because ions become free and move in solution.
Solubility in water
Yes, ionic compounds are soluble in water. Ionic compounds dissolve in water because water is polar solvent and ions get separated in water.
Q2.A student was given Mn, Zn, Fe and Cu metals. Identify which of them
(a) Will not displace H2 from HCl
(b) Will react only with steam to give H2(g)
(c) Will give H2 with 5% HNO3. Write the chemical reaction involved.
Answer
(a) Copper will not displace H2 from HCl
Reason
Copper is below hydrogen in the activity series , so it cannot displace hydrogen from dilute HCl, so reaction occurs.
(b) Iron (Fe) will react only with steam to give H2
Reason
Iron does not react with cold or hot water but it reacts with steam to produce hydrogen gas.
Fe + 4H2O →Fe3O4 + 4H2(g)
(c) Manganese will give H2 with 5% HNO3
Reason
Nitric acid is oxidising acid but very dilute nitric acid reacts with highly reactive
metal like Mn to liberate hydrogen gas.
Mn+ 2HNO3 →Mn(NO3)2 + H2(g)
Q3. Compound X and aluminium are used to join railway tracks.
(a) Identify the compound X
(b) Name the reaction
(c) Write down the reaction
Answer
(a) The compound X is Iron oxide (Fe2O3). This compound is used with aluminium to weld railway tracks.
(b) The reaction is called the ‘Thermite reaction.
(c) Fe2O3 + 2Al 2Fe + Al2O3 +heat
Q4. Carbon can reduce copper oxide to copper but not calcium oxide to calcium, why?
Answer
Carbon can reduce copper oxide to copper because copper is less reactive metal. Metals that are less reactive than carbon can be extracted from their oxides by reduction with carbon.
CuO + C → Cu+ Co
However, calcium is a highly reactive metal and is above carbon in the activity series. Therefore, carbon cannot remove calcium from calcium oxide.
Q5.A metal ‘X’ is found in the form of filings which burns vigorously when sprinkle on flame. When these filings are treated with Sulphur, a black coloured compound ‘Y’ is formed which is not attracted by magnet. ‘X’ reacts with dil. HCl to liberate hydrogen gas. Identify ‘X’ and ‘Y’. write the reaction involved.
Answer
Metal ‘X’ is iron (Fe)
Reason
(i) Iron filings burn vigorously when sprinkled in flame.
(ii) Iron reacts with Sulphur to form a black compound iron sulphide.
(iii) Iron reacts with dilute HCl to produce hydrogen gas
The compound ‘Y’ is iron sulphide (FeS). This compound is black and not attracted by a magnet.
Fe+ S →FeS
Reaction with dilute HCl
Fe + 2HCl →FeCl2 + H2
Q6. A metal ‘A’ which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature? Identify A and B. write down the reaction of oxide B with HCl and NaOH.
Answer
Metal ‘A’ is aluminium and oxide ‘B’ is aluminium oxide (Al2O3).
Aluminium is used in the thermite process and its oxide Al2O3 is amphoteric.
4Al + 3O2 →2Al2O3
Reaction of oxide B with HCl
Aluminium oxide reacts with acid to form aluminium chloride and water.
Al2O3 + 6HCl → 2AlCl3 +3H2O
Reaction of oxide B with NaOH
Aluminium oxide reacts with base to form sodium aluminate and water.
Al2O3 + 2NaOH → 2NaAlO2 +H2O
Q7.A non-metal A is an important constituent of our food and forms two oxides B and C. oxide B is toxic whereas C causes global warming.
(a) Identify A, B and C
(b) To which group of periodic table does ‘A’ belong?
Answer
(a) A= Carbon, B = Carbon monoxide and C= Carbon dioxide
Explanation
i. Carbon is present in carbohydrates, proteins and fats, so it is an important part of our food.
ii. Carbon monoxide is a toxic gas.
iii. Carbon dioxide is a greenhouse gas responsible for global warming.
( b) Carbon belongs to group 14 of the periodic table.
Q8. An element A reacts with water to form a compound B which is used in white washing. The compound B on heating forms an oxide which on treatment with water gives back B. identify A, B and C and give the reaction involved.
Answer
A = Calcium, B = Calcium hydroxide and C = Calcium oxide.
Ca + 2H2O →Ca(OH) + H2
Calcium reacts with water to form calcium hydroxide
(B) and hydrogen gas.
Ca(OH)2 → CaO + H2O
Calcium hydroxide decomposes to form calcium oxide
CaO + H2O →Ca(OH)2
Quick lime reacts with water to form calcium hyrdroxide(B) again.
Q9. A student has been collecting silver coins and copper coins. One day she observed a black coating on silver and a green coating on copper coins. Which chemical phenomenon is responsible for these coating? Write the chemical names of black and green coatings?
Answer
The phenomenon responsible for these coatings is corrosion.
Corrosion: It is the process in which metals react with air, moisture or gases and form compounds on their surface.
i. When silver reacts with sulphur compound in air (like H2S) and form a coating of silver sulphide which is black in colour.
ii. Copper reacts with oxygen, CO2 and moisture in air to form coating of basic copper carbonate which is green colour.
Q10. You are provided with three metals; sodium, magnesium and copper. Using only water as the reactant, how will you identify them?
Answer
i. Sodium reacts very vigorously with cold water. It floats on water and produces hydrogen gas with a lot of heat.
2Na + 2H2O → 2NaOH + H2
ii. Magnesium does not react with cold water but it reacts with hot water or steam to produce hydrogen gas.
Mg + H2O →MgO + H2
iii. Copper does not react with water, so Cu shows no reaction with water.
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