I. Study the action of heat on the given substances.
Write your observations, identify the products formed and write balanced chemical reaction for the same.
[copper carbonate, blue vitriol, zinc nitrate and ammonium dichromate]
II. of Study the action dilute sulphuric acid on the given substances.
Write your observation, name of the gas evolved and balanced chemical reaction in each case.
[active metal, carbonate, sulphide, sulphite]
III. Identify the metal present in the given salt using flame test.
Answers
Answer:
sorry i don't know sorry
1. Give an example of a metal which
(i) is a liquid at room temperature.
(ii) cart be easily cut with knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
Ans. (i) Mercury (Hg)
(ii) Sodium and potassium
(iii) Silver and copper
(iv) Lead -.
2. Explain the meanings of malleable and ductile.
Ans. Malleable: A metal is said to be malleable if it can be beaten into thin sheets, e.g. silver and gold are the best malleable metals.
Ductile: A metal is said to be ductile when it can be drawn into thin wires, e.g. silver and gold are the best ductile metals.
3. Why is sodium kept immersed in kerosene oil?
Ans. Sodium is highly reactive metal. It reacts with oxygen in air at room temperature, the reaction is highly exothermic. To prevent this sodium is kept preserved under kerosene. Sodium does not react with kerosene.
5. Samples of four metals A,B, C and D were taken and added to the following solutions one by one. The results obtained have been tabulated as follows.
Ans. (i) B is most reactive.
(ii) Blue colour of copper sulphate solution disappears’ arid-reddish brown copper metal is deposited on the metal B.
(iii) B > A > C > D is the order of reactivity.
6. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron’ reacts with dilute H2SO4.
Ans. When a reactive metal reacts with hydrochloric acid hydrogen gas is produced A reactive metal displaces the hydrogen from acid and release hydrogen gas.
Fe(s) .+ dil H2SO4(aq) → FeSO4(aq) + H2(g)
7. What would your observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place.
Ans. Zinc is more reactive than iron, hence when added‘ to iron (II) sulphate, it can displace iron metaliand the colour of solution fades from green to colourless due to formation of zinc sulphate. The greyish black iron metal gets deposited.
8. (i) Write the electron dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of Na2O and MgO by the transfer of electrons
(iii) What are the ions present in these compounds?
9. Why do ionic compounds have high melting points?
Ans. Ionic compounds are made up of two opposite charged ions i.e., cations (+) and anions (�), which are held together with strong electrostatic force of attraction. To break this strong bonding into ions, large amount of heat energy is required, hence the melting point of ionic compounds is high.
10. Define the following terms:
(i) Mineral (ii) Ore (iii) Gangue
Ans. (i) Mineral: The naturally occurring chemical substance which ,contains metals with, some other elements: or impurities is called mine*,
(ii) Ore: The minerals from which metals can be extracted economically on large scale are called ores.
(iii) Gangue: The impurities present in ore/minerals are called gangue.
11. Name two metals which are found in nature in free state.
Ans. Gold, platinum and silver.
12. What chemical process is used for obtaining a metal from oxide?
Ans. To obtain metals from its oxides for metals of medium reactivity one can use carbon as reducing agent and the chemical process is called reduction. Also; displacement reaction is used in which highly reactive metal acts as reducing agent. !But for the metals of high reactivity the method of electrolytic reduction in used.
e.g., 3MnO2(s) + 4Al(s) → 3Mn(l) + 2Al2O3(s) + heat
13. Metallic oxides of zinc, magnesium and copper were heated with the following metals.
In which cases will you find displacement reactions take place?
Ans.
14. Which metals do not corrode easily?
Ans. Metals which are less reactive and lie at the bottom of reactivity series i.e., silver, gold, platinum do not react with atmospheric gases and hence do not corrode easily.
15. What are alloys?
Ans. Alloys are homogeneous mixture of two or more� metals or metals or metal and non-metal.
e.g., Brass � Cu + Zn
metal + metal
Bronze � Cu + Zn
metal + metal
Steel � Fe + Ni + Cr + C
metals + non metal please follow me