Metallurgy Class 10th Science And Technology Part 1 MHB Solution

Class 10th Science And Technology Part 1 MHB Solution

Exercise
Question 1.

Write names.

a. Alloy of sodium with mercury.

b. Molecular formula of the common ore of aluminum.

c. The oxide that forms salt and water by reacting with both acid and base.

d. The device used for grinding an ore.

e. The nonmetal having electrical conductivity.

f. The reagent that dissolves noble metals.


Answer:

(a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and sodium.


(b) Bauxite. The molecular formula is Al2O3.H2O


(c) Amphoteric oxides


Eg. Al2O3 is an example of an amphoteric oxide


(d) Ball mill, is often used for grinding an ore and getting enough size reduction.


(e) Graphite is the only non-metal element that is a good conductor of electricity


(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve noble metals such as gold, palladium, and platinum.



Question 2.

Make pairs of substances and their properties



Answer:



Question 3.

Identify the pairs of metals and their ores from the following.



Answer:



Question 4.

Explain the terms.

a. Metallurgy

b. Ores

c. Minerals

d. Gangue


Answer:

(a) The process of extraction of the metals in pure form from their ores is termed as metallurgy.


(b) The minerals or deposits from which the metals can be extracted are called ores.


(c) The naturally occurring compounds of metals along with their impurities is termed as minerals.


(d) Ores contain metal compounds with some of the impurities such as sand and rocky materials and these impurities are called gangue.



Question 5.

Write scientific reason.

Lemon or tamarind is used for cleaning copper vessels turned greenish.


Answer:

Copper reacts with moist carbon dioxide in the air to form copper carbonate. The citric acid present in the lemon or tamarind neutralizes the basis copper carbonate and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic shiny appearance.



Question 6.

Write scientific reason.

Generally, the ionic compounds have high melting points.


Answer:

Ionic compounds are formed from strong electrostatic interactions between ions, which result in higher melting points and electrical conductivity compared to covalent compounds.



Question 7.

Write scientific reason.

Sodium is always kept in kerosene.


Answer:

Sodium is a very reactive metal. It is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form sodium hydroxide. This is a strongly exothermic reaction, and a lot of heat is generated.



Question 8.

Write scientific reason.

Pine oil is used in froth flotation.


Answer:

Pine oil is used in froth flotation process because it does not have an affinity towards water (because of the hydrophobic chemicals as its constituents) and it attracts impurities which can be washed away.



Question 9.

Write scientific reason.

Anodes need to be replaced from time to time during the electrolysis of alumina.


Answer:

This is because over time the graphite anode gets degraded and loses its ability to act as an electrode. Also, more impurities will stick to the electrode.




Question 10.

When a copper coin is dipped in silver nitrate solution, a glitter appears on the coin after some time. Why does this happen? Write the chemical equation.


Answer:

When Copper is dipped in silver nitrate solution, copper nitrate and silver metal are formed. A shining white deposit of silver metal is formed on the copper coin, which makes it glitter for some time.


eq:




Question 11.

The electronic configuration of metal ‘A’ is 2,8,1 and that of metal ‘B’ is 2,8,8,2. Which of the two metals is more reactive? Write their reaction with dilute hydrochloric acid.


Answer:

From the configuration,


Metal A is Sodium or Na-2,8,1


Metal B is Calcium or Ca-2,8,8,1


Metal A i.e Sodium is more reactive than Calcium. Sodium metal reactive than calcium and it even reacts when kept open in the air.


Reaction With dil.HCl:


Sodium reacts vigorously with dilute hydrochloric acid to form sodium chlorides and hydrogen.



Calcium reacts less vigorously to form calcium chloride and hydrogen gas.




Question 12.

Draw a neat labelled diagram.

Magnetic separation method.


Answer: 



Question 13.

Draw a neat labelled diagram.

Froth floatation method.


Answer:



Question 14.

Draw a neat labelled diagram.

Electrolytic reduction of alumina.


Answer:



Question 15.

Draw a neat labelled diagram.

Hydraulic separation method.


Answer: 



Question 16.

Write the chemical equation for the following events.

a. Aluminum came in contact with air.

b. Iron filings are dropped in an aqueous solution of copper sulfate.

c. A reaction was brought about between ferric oxide and aluminum.

d. Electrolysis of alumina is done.

e. Zinc oxide is dissolved in dilute hydrochloric acid.


Answer:

(a) 4Al(s) + 3O2(l) → 2Al2O3(s)


The surface of the aluminum metal is covered with a thin layer of oxide that helps protect the metal from attack by air. So, normally, aluminum metal does not react with air. If the oxide layer is damaged, the aluminum metal is exposed to attack


(b) Iron is more electropositive than copper. It can displace Copper (Cu) from its salt Copper sulfate (CuSO4) and thus its colour changes from blue to green.


Fe + CuSO4 → FeSO4 + Cu


(c) The reaction of Ferric oxide and aluminum produces aluminum oxide and iron. The chemical equation is:


3Fe3O2 + 4Al → 2Al2O3 + 6Fe


(d) The electrode reactions are:


Anode reaction: 2O2- → O2 + 4e- (Oxidation)


Cathode reaction: Al3+→ Al (l)(Reduction)


(e) ZnO(aq)+2HCl(aq)→ZnCl2(aq)+H2O(l)


Zinc chloride and water are produced in the reaction.



Question 17.

Complete the following statement using every given option.

During the extraction of aluminum…………..

a. Ingredients and gangue in bauxite.

b. Use of leaching during the concentration of ore.

c. The chemical reaction of the transformation of bauxite into alumina by Hall’s process.

d. Heating the aluminum ore with concentrated caustic soda.


Answer:

(a) Silica, Ferric Oxide, and Titanium Oxide are the impurities or gangue in Bauxite


(b) By Hall’s and Bayer’s method, where finally the concentrated alumina can be obtained by the calcination process


(c) Halls Process:




(final calcination method)


(d) Since aluminum oxide is amphoteric in nature, it reacts with NaOH to form water-soluble Sodium aluminate




Question 18.

Divide the metals Cu, Zn, Ca, Mg, Fe, Na, Li into three groups, namely reactive metals, moderately reactive metals and less reactive metals.


Answer:

Highly Reactive metals: Na, Li, Ca


Moderately Reactive Metals: Mg, Zn, Fe


Less Reactive Metals: Cu


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