Calcination

Q. Zinc sulphide exists in two different structural forms as zinc blende (FCC) and Wurtzite (HCP). What wil the coordination number of cation and anion in both the structure struct

Q. Which of the following statements is incorrect
1) NaHCO3 on heating gives NA2CO3
2) pure sodium metal dissolves in liquid ammonia to give blue solution
3) NaOH reacts with glass to give sodium silicate
4) Aluminium reacts with excess NaOH to give Al(OH)3

Q.

List of metals that can be extracted electrolytically.

Q.

What is the function of sodium cyanide in separation of ZnS and PbS ?

Q.

A blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering affect the piece of iron?

Q.

Calcination is used in metallurgy for the removal of?

1. H₂O and H₂S

2. CO₂ and H₂S

3. H₂O and CO₂

4. Water and Sulphide.

Q. When but–3-en–2–ol reacts with aq. HBr, the product formed is

1. 3–bromobut–1–ene
2. 1–bromobut–2–ene
3. A mixture of both (a) and (b)
4. 2–bromobut –2–ene

Q.

The ore which is not concentrated by froth floatation but concentrated by leaching ? Exception to froth flotation .

Q.

Name the metal oxide that can be reduced by Hydrogen.

Q. Which metal is refined by Van-Arkel method?

1. $Ni$
2. $Al$
3. $Si$
4. $Ti$

Q.

Roasting is done generally in case of the

1. Carbonate ores

2. Oxide ores

3. Sulphide ores

4. Silicate ores

Q. dissociation of Al(OH)3

Q.

Explain the following reactions

(a)Silicon is heated with methyl chloride at high temperature in the presence of copper;

(b)Silicon dioxide is treated with hydrogen fluoride;

(c) CO is heated with ZnO;

(d)Hydrated alumina is treated with aqueous NaOH solution.

Q. Red phosphorus can be prepared from white phosphorus by:

1. Heating it in an inert atmosphere for several days
2. Distilling it in inert atmosphere
3. Dissolving it in carbon disulphide and crystallising
4. Melting it and pouring the liquid into water

Q. Percentage composition of Cu , Zn , Fe in blue vitriol, white vitriol and green vitriol respectively, are _________

Q.

Why roasting Is used for sulphide ores?

Q. Ores are usually contaminated with earthly or undesired materials known as

1. Gangue
2. Dust
3. Slag
4. Lime

Q. $\alpha$-Black phosphorus is formed from:

1. $\beta$-Black phosphorus
2. White phosphorus
3. Red phosphorus
4. All of the above

Q.

Zinc blende when roasted in air gives off a gas which if allowed to escape would constitute on atmospheric pollutant. What is the gas?

Q.

In the aluminothermic process, aluminium acts as?

1. Flux

2. Reducing agent

3. Solder

4. An oxidizing agent

Q.

Aluminium is much more reactive than iron because its standard reduction potential is higher than iron. Still, aluminium is less easily corroded than iron because

1. Aluminium reacts with atmospheric carbon dioxide to form a self-protective layer of ${\mathrm{Al}}_2{\mathrm{O}}_3$

2. It has higher reducing power and forms a self-protective layer of ${\mathrm{Al}}_2{\mathrm{O}}_3$

3. It has higher reducing power and does not react with oxygen so easily

4. Both A and B

Q. In the manufacture of iron from haematite, the function of limestone is as

1. A reducing agent
2. Flux
3. Slag
4. Gangue

Q.

A metal is present in plants, bones, egg shells and sea shells. It is also used to remove oxygen from molten steel. The metal is

1. Na

2. Al

3. Ca

4. Mg

Q. Choose the correct option for the following statements
Statement - 1: Sulphide ore is firstly converted to oxide and then it is subjected to reduction for the extraction of metal.
Statement - 2: In calcination, the ore is heated in a regular supply of air in a furnace at a temperature below melting point of the calcined product.
Statement - 3: Roasting involves heating in absence of air until volatile matter escapes.
Statement - 4: In the metallurgy of aluminium, purified $A{l}_2{O}_3$ is mixed with $N{a}_{3}Al{F}_6$ or $Ca{F}_2$ which increases the melting point of the mix.

1. TTFF
2. FFFT
3. TFFT
4. TFFF

Q.

Explain the following reactions

(a) Silicon is heated with methyl chloride at high temperature in the presence of copper;

(b) Silicon dioxide is treated with hydrogen fluoride;

(c) CO is heated with ZnO;

(d) Hydrated alumina is treated with aqueous NaOH solution.

Q. Role of depressants in froth floatation method

Q. The processes of calcination and roasting in metallurgical industries, respectively, can lead to :

1. Global warming and photochemical smog
2. Photochemical smog and global warming
3. Global warming and acid rain
4. Photochemical smog and ozone layer depletion

Q.

Describe the methods generally used to extract metals.

Q. (a) Explain the following.

Q. The incorrect statement among the following is :

JEE MAINS 2021

1. $VOS{O}_4$ is a reducing agent
2. Red colour of ruby is due to the presence of $C{o}^{3+}$
3. $C{r}_2{O}_3$ is an amphoteric oxide
4. $Ru{O}_4$ is an oxidizing agent