CBSE Class 10 Science HOTs Metals and Non Metals Set 02

Physical and Chemical Properties of Metals and Non-metals, Formation and Properties of Ionic Compounds

Question. Metal oxides react generally with acids but few oxides of metal also react with bases. Such metallic oxides are
I. MgO
II. ZnO
III. \( Al_2O_3 \)
IV. CaO 
(a) I and II
(b) II and III
(c) III and IV
(d) I and IV
Answer: (b) II and III

Question. The number of valence electrons in outermost shell of the atom of a non-metal 
(a) 1, 2 or 3
(b) 3, 4 or 5
(c) 5, 6 or 7
(d) 5, 6 or 8
Answer: (c) 5, 6 or 7

Question. The image shows an incomplete chemical equation of the reaction between iron and oxygen.
\( 4Fe(s) + 3O_2(g) \rightarrow \)
Which option shows the products formed during the reaction? 
(a) \( 4FeO(s) \)
(b) \( 12FeO(s) \)
(c) \( 3Fe_4O_2(s) \)
(d) \( 2Fe_2O_3(s) \)
Answer: (d) \( 2Fe_2O_3(s) \)

Question. Which option classifies the substance based on their physical properties? 
(a) Lustrous: Graphite and silver; Good conductor of electricity: Copper; Malleable: Iron; Bad conductor of electricity: Rubber
(b) Lustrous: Copper; Good conductor of electricity: Rubber; Malleable: Iron; Bad conductor of electricity: Graphite and silver
(c) Lustrous: Copper; Good conductor of electricity: Graphite and silver; Malleable: Iron; Bad conductor of electricity: Rubber
(d) Lustrous: Copper; Good conductor of electricity: Graphite and silver; Malleable: Rubber; Bad conductor of electricity: Iron
Answer: (c) Lustrous: Copper; Good conductor of electricity: Graphite and silver; Malleable: Iron; Bad conductor of electricity: Rubber

Question. A student writes two incomplete chemical reactions.
\( X-P_4(s) + 5O_2 \rightarrow \)
\( Y-2Mg(s) + O_2(g) \rightarrow \)
Which option completes the reaction to form a balanced chemical equation? 
(a) \( X-P_5O_4(s), Y-MgO(s) \)
(b) \( X-4PO_{10}(s), Y-4MgO(s) \)
(c) \( X-P_4O_{10}(s), Y-2MgO(s) \)
(d) \( X-5P_4O_2(s), Y-Mg_2O_2(s) \)
Answer: (c) \( X-P_4O_{10}(s), Y-2MgO(s) \)

Question. A student studying the chemical properties of metals finds an incomplete chemical reaction as shown below. 
\( MgO + HNO_3 \rightarrow \)
Which option completes the reaction?
(a) \( MgO + HNO_3 \rightarrow Mg_3N_2 + 4H_2O \)
(b) \( MgO + HNO_3 \rightarrow Mg(OH)_2 + 2NO_2 \)
(c) \( MgO + HNO_3 \rightarrow Mg + NO_2 + O_2 \)
(d) \( MgO + 2HNO_3 \rightarrow Mg(NO_3)_2 + H_2O \)
Answer: (d) \( MgO + 2HNO_3 \rightarrow Mg(NO_3)_2 + H_2O \)

Question. The chemical reaction between a piece of copper and nitric acid is given by the chemical equations,
\( Cu + 2HNO_{3 (conc.)} \rightarrow Cu(NO_3)_2 + 2[H] \)
\( [H] + HNO_3 \rightarrow H_2O + NO_2 \)
What can be inferred from the chemical equation? 
(a) Copper causes the oxidation of \( HNO_3 \) to form \( NO_2 \)
(b) Hydrogen gets oxidised by \( HNO_3 \) to form water.
(c) Hydrogen gas reacts with oxygen in air to form water.
(d) Nitrate reacts with hydrogen to form \( NO_2 \) and \( H_2O \).
Answer: (b) Hydrogen gets oxidised by \( HNO_3 \) to form water.

Question. A student adds an equal amount of \( CuSO_4 \) in two beakers. He adds zinc in the beaker P and silver in beaker Q. The student observes that the colour of the solution in beaker P changes while no change is observed in beaker Q. Which option arranges metals in correct increasing order of reactivity?
(a) Ag < Zn < Cu
(b) Zn < Cu < Ag
(c) Ag < Cu < Zn
(d) Cu < Ag < Zn
Answer: (c) Ag < Cu < Zn

Question. A student learns that Na and Mg react with \( Cl_2 \) to form \( NaCl \) and \( MgCl_2 \).
\( 2Na + Cl_2 \rightarrow 2NaCl; \quad Mg + Cl_2 \rightarrow MgCl_2 \SE T.E.R.M.*]
(a) \( MgCl_2 \) is soluble in kerosene and petrol.
(b) Sodium chloride is formed by combining Na and 1 molecule of \( Cl_2 \)
(c) \( NaCl \) has strong inter-ionic bonding than \( MgCl_2 \).
(d) \( MgCl_2 \) is formed by combining one molecule of Mg.
Answer: (c) \( NaCl \) has strong inter-ionic bonding than \( MgCl_2 \).

Question. A student makes an electric circuit using an LED, a battery and connecting wires as shown in diagram. He notices that LED does not glow. He replaces distilled water by salt solution and observes that LED glows. 
How does the salt solution help the LED to glow?
(a) Salt solution is covalent in nature and conducts electricity.
(b) Salt solution has low melting point which allows current to flow through it.
(c) Salt solution has high boiling point which allows the flow of current in the circuit without getting hot.
(d) Salt solution contains ions which make it conductive and allows electricity to flow through it.
Answer: (d) Salt solution contains ions which make it conductive and allows electricity to flow through it.

Question. Which of the following non-metal is lustrous? 
(a) Oxygen
(b) Chlorine
(c) Hydrogen
(d) Iodine
Answer: (d) Iodine

Question. Generally when metals react with nitric acid the gas is produced is 
(a) \( CO_2 \)
(b) \( SO_2 \)
(c) \( NO_2 \)
(d) \( CO \)
Answer: (c) \( NO_2 \)

Question. Sodium reacts with water to form sodium hydroxide and hydrogen gas. The balanced equation which represents the above reaction is, 
(a) \( Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + 2H_2(g) \)
(b) \( 2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2(g) \)
(c) \( 2Na(s) + 2H_2O(l) \rightarrow NaOH(aq) + 2H_2(g) \)
(d) \( 2Na(s) + H_2O(l) \rightarrow 2NaOH(aq) + 2H_2(g) \)
Answer: (b) \( 2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2(g) \)

Question. Which one of the following structures correctly depicts the compound \( CaCl_2 \)? 
(a) \( Ca^{2+}[Cl]_2 \)
(b) \( [Ca] Cl_2 \)
(c) \( Ca^{2+}[Cl^-]_2 \)
(d) \( Ca Cl_2 \)
Answer: (c) \( Ca^{2+}[Cl^-]_2 \)

Question. The pair(s) which will show displacement reaction is/are 
(i) NaCl solution and copper metal
(ii) \( AgNO_3 \) solution and copper metal
(iii) \( Al_2(SO_4)_3 \) solution and magnesium metal
(iv) \( ZnSO_4 \) solution and iron metal
(a) (ii) only
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (ii)
Answer: (b) (ii) and (iii)

Question. The metal with lowest density among these
(a) Hg
(b) Ga
(c) Cs
(d) Fr
Answer: (c) Cs

Question. Aqua regia is called as royal water because it dissolves gold its composition is 1:3 concentrated.
(a) \( H_2SO_4 : HNO_3 \)
(b) \( HNO_3 : H_2SO_4 \)
(c) \( HNO_3 : HCl \)
(d) \( HCl : HNO_3 \) [KVS]
Answer: (c) \( HNO_3 : HCl \)

Question. Which of the following is purest form of carbon?
(a) Diamond
(b) Graphite
(c) Fullerene
(d) Charcoal
Answer: (c) Fullerene

Question. An element ‘X’ is yellow coloured solid, insoluble in water but soluble in carbon disulphide. It has low melting point 114.5°C. It boils at 445°C and it burns with pale blue flame forming pungent smelling gas ‘Y’ which turns moist blue litmus red and finally colourless. ‘X’ and ‘Y’ are
(a) \( C, CO_2 \)
(b) \( N, NO_2 \)
(c) \( S, SO_2 \)
(d) \( I_2, I_2O_5 \)
Answer: (c) \( S, SO_2 \)

Question. Which of the following metals liberate hydrogen gas with 5% \( HNO_3 \)?
(i) Cu
(ii) Zn
(iii) Mn
(iv) Mg
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Answer: (c) (iii) and (iv)

Question. An element ‘X’ reacts with \( O_2 \) to give a compound with a high melting point. This compound is also soluble in water. The element ‘X’ is likely to be:
(a) iron
(b) calcium
(c) carbon
(d) silicon 
Answer: (b) calcium

Question. Reaction between X and Y, forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?
(a) Has high melting point
(b) Insoluble in water
(c) Conducts electricity in molten state
(d) Occurs as solid
Answer: (b) Insoluble in water

Question. A student adds some metallic ash in water taken in a test tube. The ash gets completely dissolved in water and solution changes colour. What should be done to test the product of solution?
(a) Evaporate solution to get crystals.
(b) Test the basicity using red litmus paper.
(c) Test the acidity of solution by blue litmus.
(d) Measure the temperature using a thermometer.
Answer: (b) Test the basicity using red litmus paper.

Question. What happens when sodium is dropped in water?
(a) It catches fire and forms oxide.
(b) It absorbs heat and forms oxide.
(c) It catches fire and forms hydroxide.
(d) It absorbs heat and forms hydroxide.
Answer: (c) It catches fire and forms hydroxide.

Question. Mg reacts with 5% of \( HNO_3 \) and gives
(a) \( MgNO_3 + 2H_2 \)
(b) \( Mg(NO_3)_2 + H_2O \)
(c) \( Mg(NO_3)_2 + H_2 \)
(d) \( MgNO_3 + H_2O \)
Answer: (c) \( Mg(NO_3)_2 + H_2 \)

Question. Which of the following statement is true about the position of metals in the activity series of metals?
(a) Copper is below hydrogen but above leads.
(b) Iron is below lead and zinc.
(c) Zinc is below Mg and above Al.
(d) Mg is below Ca but above Al. 
Answer: (d) Mg is below Ca but above Al.

Very Short Answer Type Questions

Question. Read the following statements.
(P) Stainless steel does not rust.
(Q) Iron, nickel and chromium form an alloy.
Does statement (Q) present a valid explanation for statement (P)? Justify your answer. 
Answer: Yes, it does. Alloying can change the properties of a metal. Stainless steel is an alloy of iron, nickel, and chromium, which prevents the iron from rusting.

Question. A metallic element, M, has the following properties:
• floats on water
• can be cut with a knife
• occurs naturally as its chloride, of formula MCl
• its oxide dissolves in water to form the hydroxide
(a) State the method of manufacture of the metal M.
(b) Name the major byproduct obtained in the process. 
Answer: (a) Electrolysis of the molten chloride.
(b) Chlorine is obtained as byproduct in electrolysis of \( NaCl \).

Question. Give reason for the following:
(a) School bells are made up of metals.
(b) Electric wire are made up of copper. 
Answer: (a) It is because metals are sonorous, i.e. produce sound when struck with a hard substance.
(b) It is because copper is a good conductor of electricity.

Question. Write one example of each of
(a) A metal which is so soft that, it can be cut with knife and a non-metal which is the hardest substance.
(b) A metal and a non-metal which exist as liquid at room temperature. 
Answer: (a) Sodium, carbon (diamond).
(b) Mercury is liquid metal, bromine is liquid non-metal.

Question. Name the following:
(a) A metal, which is preserved in kerosene.
(b) A lustrous coloured non-metal.
(c) A metal, which can melt while kept on palm.
(d) A metal, which is a poor conductor of heat. 
Answer: (a) Sodium is preserved in kerosene.
(b) Iodine is lustrous coloured non-metal.
(c) Gallium.
(d) Lead.

Question. Give two examples each of the metals that are good conductors and poor conductors of heat respectively.
Answer: Good conductors of heat are copper and silver.
Poor conductors of heat are lead and mercury.

Question. Explain why calcium metal after reacting with water starts floating on its surface. Write the chemical equation for the reaction. Name one more metal that starts floating after some time when immersed in water. 
Answer: Calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of metal.
\( Ca(s) + 2H_2O(l) \rightarrow Ca(OH)_2 (aq) + H_2(g) \)
Magnesium reacts with hot water and starts floating due to the bubbles of hydrogen gas sticking to its surface.

Question. The way, metals like sodium, magnesium and iron react with air and water is an indication of their relative positions in the ‘reactivity series’. Is this statement true? Justify your answer with examples.
Answer: Yes, sodium reacts explosively even with cold water, it is most reactive. Magnesium reacts with hot water, it is less reactive than Na. Iron reacts only with steam which shows it is least reactive.

Question. Which of the following listed metals can displace zinc from its salt solution? Give reason of your answer along with chemical equation. 
Copper, Lead, Magnesium, Silver
Answer: Metals which are more reactive than zinc can displace Zn from its salt solution. Therefore, Magnesium can displace zinc from its salt solution.
\( Mg(s) + ZnSO_4(aq) \rightarrow MgSO_4(aq) + Zn(s) \)

Short Answer Type Questions

Question. A teacher asks her students to identify a metal, M. She gives them the following clues to help them.
(P) Its oxide reacts with both \( HCl \) and \( NaOH \).
(Q) It does not react with hot or cold water but reacts with steam.
(R) It can be extracted by electrolysis of its ore.
(a) Identify the metal.
(b) Write the chemical equations for the reaction of the metal with \( HCl \) and \( NaOH \) respectively.
(c) What would happen if the metal is reacted with iron oxide?
Answer: (a) Aluminium because it forms \( Al_2O_3 \) which is amphoteric.
(b) \( Al_2O_3 + 2NaOH \rightarrow 2NaAlO_2 + H_2O \); \( Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O \) 
(c) It would displace iron to form aluminium oxide.
\( 2Al + Fe_2O_3 \rightarrow Al_2O_3 + Fe \)

Question. The atomic number of an element is 20. Write its electronic configuration. State whether this element is a metal or a non-metal. What is its valency? Write the name and formula of the compound which this element forms with chlorine. 
Answer: The electronic configuration of calcium (Z = 20) is 2, 8, 8, 2. Since it has two valence electrons its valency is 2 and due to presence in group 2, it is a metal. The name of compound calcium forms with chlorine is calcium chloride and its formal is \( CaCl_2 \).

Question. State three reasons for the following facts:
(a) Sulphur is a non-metal
(b) Magnesium is a metal
One of the reasons must be supported with a chemical equation. 
Answer:
(a) Sulphur is a non-metal:

(i) Poor conductor of heat and electricity.

(ii) Neither malleable nor ductile.

(iii) \( S + O_2 \rightarrow SO_2 \); Sulphur dioxide is acidic oxide. \( SO_2 + H_2O \rightarrow H_2SO_3 \) (Sulphurous acid)

(b) Magnesium is a metal:

(i) Good conductor of heat and electricity.

(ii) Malleable and ductile.

(iii) \( 2Mg + O_2 \rightarrow 2MgO \); Magnesium oxide is basic in nature. \( MgO + H_2O \rightarrow Mg(OH)_2 \) (Magnesium hydroxide)

Question. Explain the following:
(a) Sodium chloride is an ionic compound which does not conduct electricity in solid state where as it does conduct electricity in molten state as well as in aqueous solution.
(b) Reactivity of aluminium decreases if it is dipped in nitric acid.
(c) Metals like calcium and magnesium are never found in their free state in nature. 
Answer:
(a) • Sodium chloride is an ionic compound because it is made up of \( Na^+ \) and \( Cl^- \) ions.
• It does not conduct electricity in solid state because ions are not free to move.
• It conducts electricity in molten state because ions are free to move.
(b) It is due to formation of oxide layer on its surface which makes it passive (less reactive). \( HNO_3 \) is a good oxidising agent.
(c) It is because Mg and Ca are highly reactive, react with other elements to form compounds, therefore, are not found in free state.

Question. You are given samples of three metals: Sodium, magnesium and copper. Suggest any two activities to arrange them in order of decreasing activity. 
Answer: Activity 1: Sodium reacts with cold water to form sodium hydroxide and hydrogen gas. \( 2Na (s) + 2H_2O (l) \rightarrow 2NaOH (aq) + H_2 (g) \). Magnesium does not react with cold water but with hot water to form magnesium hydroxide and hydrogen gas. \( Mg (s) + 2H_2O (l) \rightarrow Mg(OH)_2 (aq) + H_2 (g) \). Hence sodium is more reactive than magnesium.
Activity 2: \( Mg (s) + CuSO_4 (aq) \rightarrow MgSO_4 (aq) + Cu (s) \). \( Cu (s) + MgSO_4 (aq) \rightarrow \) No reaction. So magnesium is more reactive than copper. Concluding from activity 1 and 2, Na > Mg > Cu.

Question. (a) Write the electron dot structures for potassium and chlorine.
(b) Show the formation of \( KCl \) by the transfer of electrons.
(c) Name the ions present in this compound, \( KCl \). 
Answer: (a) K (2, 8, 8, 1); Cl (2, 8, 7).
(b) \( K \rightarrow K^+ + e^- \); \( Cl + e^- \rightarrow Cl^- \). K transfers its valence electron to Cl.
(c) \( KCl \) has \( K^+ \) and \( Cl^- \) ions.

Long Answer Type Questions

Question. (a) Write electron dot structure for chlorine (At No. 17) and calcium (At No. 20). Show the formation of calcium chloride by the transfer of electrons.
(b) Identify the nature of the above compound and explain three physical properties of such compounds. 
Answer: (a) Cl: (2, 8, 7); Ca: (2, 8, 8, 2). Ca donates two electrons, and each of the two Cl atoms receives one electron to form \( CaCl_2 \).
(b) It is ionic compound. Physical properties:

(i) It is hard and solid.

(ii) It has high melting and boiling point.

(iii) It is soluble in water.

Question. Distinguish between metals and non-metals on the basis of (a) two physical and (b) three chemical properties. 
Answer:
(a) Physical properties:

• Metals are malleable and ductile; Non-metals are brittle.
• Metals are good conductors of heat and electricity; Non-metals are poor conductors.

(b) Chemical properties:

• Metals form basic oxides; Non-metals form acidic or neutral oxides.
• Metals react with acids to liberate hydrogen gas; Non-metals do not usually react with acids.
• Metals are electropositive (lose electrons); Non-metals are electronegative (gain electrons).