Zone Refining

Q.

Explain the preparation of sodium fusion extract

Q. kclo3 decomposes to form kcl and 02.if the volume of o2 obtained in this reaction is 1.12 l at stp, weight of kcl formed in this reaction

Q.

What is the role of cryolite in the metallurgy of aluminium?

Q. 1.5g of an alkaline earth metal reacts with 0.35 g of nitrogen to form its nitride.Then the metal is? A)Mg B)Ca C)Sr D)Be

Q. explain how gold is extracted

Give answer properly and in simple language

Q. When an impurity in a metal has a greater affinity towards oxygen and is more easily oxidized than the metal itself, then the metal is refined by:

1. Cupellation
2. Zone refining
3. Poling
4. Electrolytic process

Q. Zone refining is based on the principle that the impurities are more soluble in the melt than in the solid metal.

1. True
2. False

Q. Assertion :Zone refining method is used to produce pure metals which are used as semiconductors. Reason: Semiconductors are used in highly pure form.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

Name the method of purification for producing semi-conductor or other metals of very high purity.

Q. The process of zone refining is used in the purification of :

1. $Al$
2. $Cu$
3. $Ag$
4. $Ge$

Q. Method used for obtained highly pure silicon, used as a semiconductor material, is

1. oxidation
2. electrochemical
3. crystallization
4. zone refining

Q. Zone refining is used for the purification of

1. $Ge$
2. $Si$
3. $Ga$
4. $Se$

Q.

Explain:

Zone refining

Column chromatography .

Q.

Match the items of Column I with the items of Column II and assign the correct code.
$\begin{array}{cc}ColumnI& ColumnII\\ A.Colouredbands& 1.Zonerefining\\ B.Impuremetaltovolatilecomplex& 2.Fractionaldistillation\\ C.PurificationofGeandSi& 3.Mon{d}^{\prime }sprocess\\ D.Purificationofmercury& 4.Chromatography\\ & 5.Liquation\end{array}$
Codes
A B C D A B C D
(a) 1 2 4 5 (b) 4 3 1 2
(c) 3 4 2 1 (d) 5 4 3 2

Q. Draw a neat and labelled diagram of zone refining process.

Q. Zone refining is used for the purification of

1. $Ge$
2. $Si$
3. $Ga$
4. $Se$

Q. then why cant the zone refining done in vaccum?

Q.

Give reasons:

(i) Conc. HNO₃ can be transported in aluminium container.

(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.

(iii) Graphite is used as lubricant.

(iv) Diamond is used as an abrasive.

(v) Aluminium alloys are used to make aircraft body.

(vi) Aluminium utensils should not be kept in water overnight.

(vii) Aluminium wire is used to make transmission cables.

Q.

77 ) Mention the appropriate term corresponding to following sentence

(iv) The hardest compound of silicon used in all kinds of grinding wheels

Q. Impurities of sulphur, silicon, and phosphorus can be removed from cast iron by adding:

1. carbon which reduces the impurities
2. water which dissolves the impurities
3. limestone which changes impurities into oxides and pass into slag
4. iron oxide which reacts with impurities by forming slag

Q. Explain zone refining.

Q.

How are metals used as semiconductors refined? What is the principle of the method used like germanium, silicon etc?

Q. When an impurity in a metal has a greater affinity towards oxygen and is more easily oxidized than the metal itself, then the metal is refined by:

1. Cupellation
2. Zone refining
3. Poling
4. Electrolytic process

Q. Semiconductor materials like $Si$ and $Ge$ are usually purified by:

1. distillation
2. zone refining
3. electrolytic refining
4. liquation

Q. Which of the following is used as a method of purification for silicon?

1. Electrolytic refining
2. Liquation
3. Zone refining
4. Distillation

Q. extraction of zinc

Q. Which method is used to get very pure germanium used in semiconductor ?

1. Liquation
2. Vapour-phase refining
3. Zone-refining
4. Electrolysis

Q. Match the column I with column II and mark the appropriate choice.

	Column I		Column II
(A)	Metals used as semiconductors	(i)	Aluminium
(B)	Electrolytic reduction	(ii)	Zone refining
(C)	Cyanide process	(iii)	Dressing of $ZnS$
(D)	Froth floatation process	(iv)	Extraction of $Ag$

1. (A) $\to$(i), (B)$\to$(iii), (C)$\to$(ii), (D) $\to$ (iv)
2. (A) $\to$(iii), (B)$\to$(iv), (C)$\to$(ii), (D) $\to$ (i)
3. (A) $\to$(iv), (B)$\to$(ii), (C)$\to$(iii), (D) $\to$ (i)
4. (A) $\to$(ii), (B)$\to$(i), (C)$\to$(iv), (D) $\to$ (iii)

Q. Draw labelled diagram of Zone refining process. In which this process is useful?

Q.

You are an alchemist who is trying to remove hard lead impurity from Crude silver. You can only use thermal refining by using a blast of air. What would you use?

1. Van Arkel-de Boer Refining

2. Mond’s process

3. Linz-Donawitz process

4. Cupellation