Tag: occurrence of carbon compounds in nature

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Questions Related to occurrence of carbon compounds in nature

Multiple choice chemistry occurrence of carbon compounds in nature importance of carbon covalent bonding in carbon compounds carbon and its forms
Carbon is a versatile element.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carbon is a versatile element. Statement is True.
Carbon is a versatile element and is found in many different chemical compounds, including those found in space. Carbon is versatile because it can form single, double, and triple bonds. It can also form chains, branched chains, and rings when connected to other carbon atoms.

Multiple choice chemistry occurrence of carbon compounds in nature importance of carbon covalent bonding in carbon compounds carbon and its forms

Using the given hints, identify the option with correct coal product and its use.
(1)$\;\;$Almost pure form of carbon.

  1. Coke, manufacture of steel

  2. Coal tar, manufacture of paints

  3. Coke, manufacture of plastics

  4. Coal tar, extraction of metals
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Coke has few impurities and high carbon content. Coke is used as a fuel and as reducing agent in smelting iron ore in blast furnace for production of steel. The bulk specific gravity of coke is around 0.77 and is highly porous.

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

What is used to measure the calorific value of a substance?

  1. Barometer

  2. Bomb calorimeter

  3. Spectrometer

  4. Combustion chamber
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Barometer: To measure pressure.

Bomb calorimeter: To measure the heat output of combustion.

Spectrometer: To measure the absorption of light.

Combustion chamber: Chamber used for combustion.

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

Calorific value of ethane, in kJ/g if for the reaction is: $2C _2H _6+7O _2\rightarrow 4CO _2+6H _2O;\Delta H=-745.6$ kcal.

  1. $-12.4$
  2. $-52$
  3. $-24.8$
  4. $-104$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heat of combustion of ethane $=-\frac{745.6}{2}=-372.8\;Kcal\;mol^{-1}=-1559.79\;KJ\;mol^{-1}$       ($1\;cal.=4.2\;J$)

$calorific\; value=\dfrac{heat\;of\;combustion }{gram\;molecular\;weight\;of\;fuel}=-\dfrac{1559.79}{30}=-51.98\approx 52\;KJgm^{-1}$

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

Calorific value of ethane, in kJ/g if for the reaction :


 $2C _2H _6 + 7O _2 \rightarrow 4CO _2 + 6H _2O; \Delta H = -745.6\ kcal$

  1. $-12.4$
  2. $-52$
  3. $-24.8$
  4. $-104$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$2C _2H _6+7O _2\rightarrow 4CO _2+6H _2O$; $\Delta H=-745.6KCal$


$\therefore$ Heat of combustion of ethane $=\cfrac {-745.6}{2}=-372.8 Kcal$

                                                                              $=-372.8 \times 4.18 kJ$

                                                                              $=-1558.3 kJ$

Calorific value $=\cfrac {\text{Heat of combustion}}{\text{Molecular weight of }C _2H _6}=- \cfrac {1558.3}{30}=-51.9=-52\ kJ/g$ .


Therefore, the correct option is B.

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

The heat of combustion of carbon is $94$kcal. The calorific value of carbon is about:

  1. $7.8$ kcal
  2. $15.6$ kcal
  3. $47.0$ kcal
  4. $94$ kcal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The calorific value of a substance is the heat which it releases during combustion of its $1\text{ } gm$ solid.

Therefore, $\text{Calorific value }(C.V)=\cfrac{\text{Heat of combustion}}{\text{Mol. weight}}\ C+O _2\longrightarrow CO _2;\triangle H=-94Kcal\C.V=\cfrac{-94}{12}Kcal\=-7.83Kcal$

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

Gross and net calorific value of fuel will be the same :

  1. if its ash content is zero

  2. under no circumstances

  3. if its carbon content is very low

  4. if its hydrogen/hydrogen compound content is zero
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The gross or high heating value is the amount of heat produced by the complete combustion of a unit quantity of fuel. 


The net, or lower, value is determined by calculation and equals the gross calorific value minus the latent heat of the water vapor formed from the combustion of hydrogen and from any moisture present in the fuel. 

Gross and net calorific value of a fuel will be the same if its hydrogen compound content is zero.

Hence, option $D$ is correct.

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.

  1. sulphur

  2. oxygen

  3. hydrogen

  4. carbon
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The energy contained in a fuel or food, determined by measuring the heat produced by the complete combustion of a specified quantity of it. This is now usually expressed in joules per kilogram. Oxygen present in dry gaseous fuel does not contribute to its calorific value.