Roasting

Q. The solid copper obtained from copper matte has blistered appearance. It is due to

1. evolution of $S{O}_2$
2. impurities of $FeS$
3. impurities of $FeO$
4. evolution of $N{O}_2$

Q. Zinc blende on roasting in air gives:

1. Zinc Carbonate
2. $S{O}_2$ and $ZnO$
3. $ZnS$ and $ZnS{O}_4$
4. $C{O}_2$ and $ZnO$

Q. Choose the correct option using the code regarding roasting process.
I) It is the process of heating the ore in air in a reverberatory furnace to obtain the oxide.
II) It is an exothermic process.
III) It is used for the concentration of sulphide ore.
IV) It removes easily oxidisable volatile impurities present in the concentrated ore.

1. I, II and III
2. I, II and IV
3. I, III and IV
4. I, II, III and IV

Q.

Why copper matte is put in silica lined converter?

Q.

Which combination cannot be used for thepreparation of hydrogen gas in the
laboratory?

I.Zn/conc.H${}_2$SO${}_4$(Impure Zinc is used)

II.Zn/dil.HNO${}_3$ (Impure Zinc is used)

III.Zn/dil.H${}_2$SO${}_4$ (Very highly pure Zn is used)

1. II only

2. III only

3. I II and III

4. I and II

Q.

Giving examples, differentiate between ‘roasting’ and ‘calcination’.

Q.

Giving examples, differentiate between roasting' and calcination'

Q.

Partial roasting of sulphide ores is done in the metallurgical operation of copper. Why?

Q. Which of the following is an oxide ore?

1. Pitchblende
2. Galena
3. Fluoruspar
4. None of the above

Q. Iron is obtained on a large scale from $F{e}_2{O}_3$ by

1. Reduction with $Al$
2. Reduction with $CO$
3. Reduction with $H_2$
4. Reduction with sodium

Q. Copper matte produced during the extraction of copper contains

1. $C{u}_{2}S$
2. $FeS$
3. $CuS{O}_4$
4. $Cu{F}_2$

Q. Roasting is usually performed in :

1. 
   Blast furnace
2. 
   Reverberatory furnace
3. 
   Bessemer's converter
4. 
   Electric furnace

Q. Zinc blende on roasting in air gives:

1. $ZnC{O}_3$
2. $ZnO$ and $S{O}_2$
3. ZnS and $ZnS{O}_4$
4. $ZnO$ and $C{O}_2$

Q. Which of the followng is correct?

1. Source of Galium include ores of Aluminium, Zinc and Germanium
2. Source of Indium include ores of ZnS & PbS ores
3. Source of Thallium include ores of ZnS & PbS ores
4. All of the above.

Q. Which among the following is not an ore of zinc?

1. Calamine
2. Zincite
3. Chalcopyrite
4. Blackjack

Q. Which of the following sets is/are true?

1. Indian saltpeter​ - Nitrate ore
2. Fluoruspar - Halide ore
3. Pitchblende - Sulphide ore
4. Galena - Sulphate ore

Q. Sulfide ores are common for the metals.
(IIT-JEE, 2013)

1. Ag, Cu and Pb
2. Ag, Cu and Sn
3. Ag, Mg and Pb
4. Al, Cu and Pb

Q. Why is zinc not extracted from zinc oxide through reduction using $CO?$

Q. $Pb$ and $Sn$ are extracted from their chief ore respectively by

1. Self reduction and carbon reduction
2. Electrolysis and self-reduction
3. Self reduction and electrolysis
4. Carbon reduction and self-reduction

Q. In which direction is the flow of electrons in an indirect redox reaction?

Q. Zinc blende on roasting in air gives:

1. $ZnC{O}_3$
2. $ZnO$ and $S{O}_2$
3. ZnS and $ZnS{O}_4$
4. $ZnO$ and $C{O}_2$

Q. Account for the following:
Iron on reaction with $HCl$ forms $FeC{l}_2$ and not $FeC{l}_3$.

Q. A metal occurs in nature as its ore X which on heating in air convert to Y. Y reacts with unreacted X to give the metal. The metal is:

1. Hg
2. Cu
3. Zn
4. Fe

Q. Define pyrometallurgy, hydrometallurgy, electrometallurgy-
State third law of thermodynamics and explain residual entropy of the substance. The solubility of nitrogen gas at $1atm$ pressure and ${25}^{o}C$ is $6.8\times {10}^{-4}mole/{dm}^3$. Calculate the solubility of $N_{2\left(g\right)}$ at this temp. and pressure is $0.78atm$.

Q. Assertion :Both boron and silicon form binary compounds with several metals to give borides and silicide. Reason: These borides and silicide react with $H_{3}P{O}_4$ to give mixture of boranes and silanes.

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. $A$ and $B$ are two ores of copper.
$A$ undergoes calcination to form a solid, $C{O}_{2\left(g\right)}$ and $O_{2\left(g\right)}$
$B$ undergoes roasting to form a solid and a gas $C$ which turns acidified $K_{2}C{r}_2{O}_7$ to green solution.
$B$ also reacts with dil $HCl$ to form a solid and gas $D$ which turns lead acetate solution black. $D$ also reacts with $C$ to form colloidal sulphur in the presence of moisture.

The nature of the gas ($D$) and hybridization of the central atom is respectively:

1. Weakly acidic, $s{p}^3$
2. Strongly acidic, $s{p}^3$
3. Weakly acidic, $s{p}^2$
4. Strongly acidic, $s{p}^2$

Q. Automobile airbags are inflated with $N_2$ gas which is formed by the decomposition of solid sodium azide $\left(Na{N}_3\right)$. The other product is Na $-$ metal. Calculate the volume of $N_2$ gas at ${27}^{\circ }C$ and 756 Torr formed by the decomposing of 125 gm of sodium azide:

1. 61.4 L
2. 71.4 L
3. 51.4 L
4. 41.4 L

Q. Differentiate between roasting and calcination with examples.

Q. Match the conversion in $ColumnI$ with the type(s) of reaction(s) given in $ColumnII$.
$$\begin{array}{cccc}& ColumnI& & ColumnII\\ A.& PbS⟶PbO& p.& Roasting\\ B.& CaC{O}_3⟶CaO& q.& Calcination\\ C.& ZnS⟶Zn& r.& Carbonreduction\\ D.& C{u}_{2}S⟶Cu& s.& Self-reduction\end{array}$$

1. $A.\to p;B.\to q;C.\to p,r;D.\to p,s.$
2. $A.\to p,s;B.\to q;C.\to p,q,r;D.\to p,s.$
3. $A.\to s;B.\to q;C.\to p,r;D.\to p,s.$
4. $A.\to p,s;B.\to q,r;C.\to p,r;D.\to p,s.$

Q. Which acts as poison for Pd-charcoal in Lindlar's catalyst?

1. $BaS{O}_4$
2. Quinoline
3. Both $A$ and $B$
4. None of the above