NIOS Class 10 Science Worksheet 27 Questions Answers – Metals and Non-Metals

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.

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 H_2(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 + 4H_2(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 + H_2(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.