CARBON AND ITS COMPOUNDS– Versatile Nature of Carbon

 CARBON AND ITS COMPOUNDS

Carbon Properties
01.	What are the two properties of Carbon which lead to the huge number of Carbon compounds we see around us ?
02.	Carbon(Group 14) element in the periodic table is known to form compounds with many elements. Write an example of a compound formed with a.Chlorine (Group 17 of periodic table)      b.Oxygen (Group 16 of periodic table)
03.	Carbon can neither form C4+ cation nor C4- anions. Why ?	2023
04.	Give reason why carbon can neither form C4+ cations nor C4- anions but form covalent compounds.	2024
05.	List two properties by virtue of which carbon form a large number of compounds.	2024
06.	State reasons why 1.Carbon forms strong bonds and stable compounds with most other elements 2.The melting and boiling points of covalent compounds are low.	2023
07.	Carbon compounds have low melting and boiling points ?	2022
08.	“Carbon prefers to share its valence electrons with other atoms of carbon or with atoms of other elements rather than gaining or losing the valence electrons in order to attain noble gas configuration.” Give reason to justify this statement.	2022
09.	State the reason why a)     Carbon compounds have low melting and boiling points. b)       Carbon compounds do not conduct electricity c)     Carbon can form only covalent compounds.	2022
10.	‘Two different forms of carbon – diamond and graphite have different structures and very different physical properties even though their chemical properties are same.” Explain why	2022
11.	State the reasons, why carbon cannot (i)                Lose four electrons to form C4+ cations (ii)             Gain four electrons to form C4- anions.	2022

	How does carbon overcome this problem to form compounds ?
12.	Write the name of an allotrope of carbon.	2021
13.	‘Carbon forms strong bond with most other elements making the compounds exceptionally stable.” Give reason to justify this statement.	2021
14.	The table shows the electronic structure of four elements. a.Identify which element(s) will form covalent bond with carbon. b.“Carbon reacts with an element in the above table to form several compounds.” Give suitable reasons.	2022 SP
15.	List two properties of carbon which lead to the huge number of carbon compounds we see around us, giving reason for each.	2019
16.	a.State the reason why carbon can neither form C4+ cations nor C4- anions, but forms covalent bonds. Also state reasons to explain why covalent compounds i.Are bad conductors of electricity ii.Have low melting and boiling points.	2019
17.	Give reason why carbon can neither form C4+ cations nor C4- anions, but forms covalent compounds which are bad conductor of electricity and have low melting and boiling points ?	2017
18.	Expalin, giving reason, why carbon neither forms C4+ cations nor C4- anions, but forms covalent compounds which are bad conductor of electricity and have low melting and boiling point.	2017
19.	Explain the reason why carbon forms compounds mainly by covalent bonds. State two main reasons responsible for carbon making a large number of compounds. Also explain why compounds formed by carbon with most other elements are exceptionally stable.	2017
20.	a.State two main reasons for carbon forming a very large number of compounds. b.Give reason why carbon forms compounds. i. Namely by covalent bonding ii.Have low melting and boiling points.	2017 SP
Catenation
01.	Catenation is the ability of an atom to form bonds with other atoms of the same element. It is exhibited by both carbon and silicon. Compare the ability of catenation of the two elements. Give reasons.

02.	Carbon, a member of group 14, forms a large number of carbon compounds estimated to be about three million. Why is this property not exhibited by other elements of this group ? Explain	2020
03.	State any two reasons for carbon forming a large number of compounds. Why does carbon form compounds i.Mainly by covalent bonding ii.Having low melting and boiling points.	2020
04.	Why does carbon show catenation to maximum extent ? List two reasons.	2020
05.	The number of carbon compounds is more than those formed by all other elements put together. Justify this statement by giving two reasons.	2021 SP
06.	Define Catenation.	2020 SP
Tetravalency
01.	Carbon has four electorn in its valence shell. Which type of compound can be formed by carbon and why ? Give any one example of such compound.	2018

Chemistry class XI question paper based on redox reactions and chemical equilibrium

about the relationship between Kc and Kp is 

SUB:  Chemistry      

CLASS:  11th           

MM:  40

General instructions

Question no.01 to 10 carry one marks.

Question no.11 to 14 carry two marks.

Question no. 15 to 17 carry three marks.

Question no.18 to 19 carry four marks.

Question no. 20 carry five marks.

 

SECTION A- (1M)

Q.1. We know about the relationship between Kc and Kp is 

Kp = Kc (RT)∆n

What will be the value of ∆n for the reaction

NH4Cl (s) → NH3 (g) + HCl (g)

(i) 1

(ii) 0.5

(iii) 1.5

(iv) 2

 

Q.2. In the case of the reaction

H2(g) + I2(g) → 2HI (g), 

the standard free energy is given as 

∆G > 0.

The equilibrium constant (K) will be ___

(i) K = 0

(ii) K > 1

(iii) K = 1

(iv) K < 1

 

Q.3.Which of the following is not the general feature of equilibria involving physical processes?

(i) Equilibrium is possible only in the closed system at the given temperature.

(ii) All measurable properties of the given system remain constant.

(iii) All the physical processes stop at equilibrium.

(iv) The opposing process occurs at the same rate, and there is the dynamic, however stable condition.

 

 

Q.4.PCl5, PCl3, and Cl2 are at equilibrium at 500K in the closed container, and their concentrations are given as 0.8 × 10–3mol L–1, 1.2 × 10–3 mol L–1, and 1.2 × 10–3 mol L–1 respectively. The value of Kc for the given reaction

PCl5 (g) PCl3 (g) + Cl2 (g) will be,

 

 

(i) 1.8 × 103mol L–1

(ii) 1.8 × 10–3

(iii) 1.8 × 10–3 L moL–1

(iv) 0.55 × 104

 

Q.5. The acidity of the compound BF3 could be explained based on which among the following concepts?

(i) Arrhenius’s concept

(ii) Bronsted Lowry’s concept

(iii) Lewis’s concept

(iv) Bronsted Lowry as well as Lewis’s concept.

 

Q.6. Which of the following is not a redox reaction?

(a) CaCO3 → CaO + CO2

(b) O2 + 2H2 → 2H2O

(c) Na + H2O → NaOH + 1/2H2

(d) MnCl3 → MnCl2 + 1/2 Cl2

 

Q.7.The most powerful oxidising agent among the following is:

(a) H2SO4

(b) H3BO3

(c) HPO3

(d) H3PO4

 

Q.8.The oxidation number of Cr in K2Cr2O7 is:

(a) -6

(b) +6

(c) +2

(d) -2

 

 

 

Q9. Consider the following reaction:

Zn + Cu2+ → Zn2+ + Cu

With reference to the above, which one of the following is the correct statement?

(a) Zn is reduced to Zn2+ ions.

(b) Zn is oxidised to Zn2+ ions.

(c) Zn2+ ions are oxidised to Zn.

(d) Cu2+ ions are oxidized to Cu.

 

 

Q.10. Reduction never involves:

(a) gain of electrons

(b) decrease in oxidation number

(c) loss of electrons

(d) decrease in valency of electropositive component

 

 

 

                  SECTION- B (2M EACH)

 

Q.11. The value of Kc for the given reaction 

    2HI (g) ⇋ H2 (g) + I2 (g) is 1 × 10-4

    At the given time, the composition of the reaction mixture is   given as follows;

 [HI] =2 × 10-5 mol, [H2] =1 × 10-5 mol as well as [I2] =1 × 10-5 mol.

 

 Q.12. Predict whether the solutions for the following salts are neutral, acidic or basic: NaCl, KBr, NH4NO3, and KF.

In which direction would the reaction proceed?

 

Q.13. Calculate the oxidation number of phosphorus in the following species.

(a) HPO32- and

(b) PO43-

 

Q.14 Balance the following redox reactions by half reaction method   

   Cr2O7 2-- + Fe2+(aq.)  → Cr3+(aq.) + Fe3+ (aq.)  (in acidic solution) 

 

 

 

 

​                 SECTION- C (3M EACH)

Case Study 1:

The idea of oxidation number has been invariably applied to define oxidation, reduction, oxidising agent (oxidant), reducing agent (reductant) and the redox reaction. To summarise, we may say that:

 

 

Oxidation: An increase in the oxidation number of the element in the given substance.

Reduction: A decrease in the oxidation number of the element in the given substance.

Oxidising agent: A reagent which can increase the oxidation number of an element in a given substance. These reagents are called as oxidants also.

Reducing agent: A reagent which lowers the oxidation number of an element in a given substance. These reagents are also called as reductants.

Redox reactions: Reactions which involve change in oxidation number of the interacting species.

Types of Redox Reactions

1.) Combination reactions -A combination reaction may be denoted in the manner:

A + B → C

Either A and B or both A and B must be in the elemental form for such a reaction to be a redox reaction. All combustion reactions, which make use of elemental dioxygen, as well as other reactions involving elements other than dioxygen, are redox reactions. Some important examples of this category are:

2.) Decomposition reactions- Decomposition reactions are the opposite of combination reactions. Precisely, a decomposition reaction leads to the breakdown of a compound into two or more components at least one of which must be in the elemental state.

Examples of this class of reactions are:

It may carefully be noted that there is no change in the oxidation number of hydrogen in methane under combination reactions and that of potassium in potassium chlorate in reaction. This may also be noted here that all decomposition reactions are not redox reactions. For example, decomposition of calcium carbonate is not a redox reaction.

3.) Displacement reactions- In a displacement reaction, an ion (or an atom) in a compound is replaced by an ion (or an atom) of another element. It may be denoted as:

X + YZ → XZ + Y

Displacement reactions fit into two categories: metal displacement and non-metal displacement.

(a) Metal displacement: A metal in a compound can be displaced by another metal in the uncombined state. Metal displacement reactions find many applications in metallurgical processes in which pure metals are obtained from their compounds in ores.

(b) Non-metal displacement: The non-metal displacement redox reactions include hydrogen displacement and a rarely occurring reaction involving oxygen displacement. All alkali metals and some alkaline earth metals (Ca, Sr, and Ba) which are very good reductants, will displace hydrogen from cold water. Many metals, including those which do not react with cold water, are capable of displacing hydrogen from acids. Dihydrogen from acids may even be produced by such metals which do not react with steam. Cadmium and tin are the examples of such metals.

4.) Disproportionation reactions – Disproportionation reactions are a special type of redox reactions. In a disproportionation reaction an element in one oxidation state is simultaneously oxidised and reduced. One of the reacting substances in a disproportionation reaction always contains an element that can exist in at least three oxidation states. The element in the form of reacting substance is in the intermediate oxidation state; and both higher and lower oxidation states of that element are formed in the reaction. The decomposition of hydrogen peroxide is a familiar example of the reaction, where oxygen experiences disproportionation.

Here the oxygen of peroxide, which is present in –1 state, is converted to zero oxidation state in O2 and decreases to –2 oxidation state in H2O.

 

 

Q.15.

(i) In … an ion (or an atom) in a compound is replaced by an ion (or an atom) of another element.

a) displacement reaction

b) decomposition reaction

c) disproportionation reaction

d) combination reaction

 

ii) … leads to the breakdown of a compound into two or more components at least one of which must be in the elemental state.

 a) displacement reaction

 b) decomposition reaction

 c) disproportionation reaction

 d) combination reaction

 

iii) In …. an element in one oxidation state is simultaneously oxidised and reduced.

a) displacement reaction

b) decomposition reaction

c) disproportionation reaction

d) combination reaction

 

 

Case Study 1: Le Chatelier’s principle is also known as the equilibrium law, used to predict the effect of change on a system at chemical equilibrium. This principle states that equilibrium adjusts the forward and backward reactions in such a way as to accept the change affecting the equilibrium condition. When factor-like concentration, pressure, temperature, and inert gas that affect equilibrium are changed, the equilibrium will shift in that direction where the effects caused by these changes are nullified. This principle is also used to manipulate reversible reactions in order to obtain suitable outcomes.

 

Q16.Which one of the following conditions will favour the maximum formation of the product in the reaction?

 

(i)

(a) Low temperature and high pressure
(b) Low temperature and low pressure
(c) High temperature and high pressure
(d) High temperature and low pressure

 

 

(ii)For the reversible reaction,

The equilibrium shifts in forwarding direction
(a) by increasing the concentration of NH3(g)
(b) by decreasing the pressure
(c) by decreasing the concentrations of N2(g) and H2(g)
(d) by increasing pressure and decreasing temperature.

 

(iii)Favourable conditions for manufacture of ammonia by the reaction

(a) low temperature, low pressure and catalyst
(b) low temperature, high pressure and catalyst
(c) high temperature, low pressure and catalyst
(d) high temperature, high pressure and catalyst

 

Q.17. Justify that the following reactions are redox reactions:
(a) CuO (s) + H2(g) —–> Cu(s) + H20(g)
(b) Fe2O3 (s) + 3CO(g) —-> 2Fe(s) + 3CO2(g)
(c) 4BCl3(g) +3LiAlH4(s) ——> 2B2H6(g) + 3LiCl(s) + 3AlCl3(s)

 

                     SECTION -D (4M EACH)

 

Q.18.Write formulas for the following compounds:
(a) Mercury (II) chloride, 

(b) Nickel (II) sulphate,

(c) Tin (IV) oxide, 

(d) Thallium (1) Sulphate

 

Q.19.What is the effect of:
(i) addition of H2 

(ii) addition of CH3OH
(iii) removal of CO

(iv) removal of CH3OH

 

 

 

 

 

 

                   SECTION -E (5 M)

Q.20. At 473 K, the equilibrium constant Kc for the decomposition of phosphorus pentachloride (PCl5) is 8.3 x 10-3 . if decomposition proceeds as:

(a) Write an expression for Kc for the reaction
(b) What is the value of Kc for the reverse reaction at the same temperature.
(c) What would be the effect on Kc 

if
(i) More of PCl5is added 

(ii) Temperature is increased.