Tag: chemistry

Questions Related to chemistry

Which of the following reaction is not endothermic in nature?

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. breaking of bonds

  2. digestion of food

  3. combustion of Carbon

  4. evaporation of water

Show answer
Correct Option: C
Explanation:

Combustion or burning is a high temperature exothermic redox chemical reaction between fuel and an oxidant oxygen. Evaporation and sublimation are phase change physical process of water. Digestion of food is breakdown of larger molecules into small ones by bong breaking which is an endothermic process.

Select the correct alternative.

Which of the following reactions are exothermic in nature?

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. Combustion of Carbon

  2. Bond breaking

  3. Bond formation

  4. Both (a) and (c)

Show answer
Correct Option: D
Explanation:

Combustion or burning is a high temperature exothermic redox chemical reaction between fuel and an oxidant oxygen. Bond breaking requires energy to be supplied for bond dissociation so it is an endothermic process while bond formation releases energy so that the product becomes stable which is an exothermic process.

Which of the following is an exothermic process?

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. Dilution of sulphuric acid

  2. Sublimation of dry ice

  3. Evaporation of water

  4. Melting of ice

Show answer
Correct Option: A
Explanation:

A large amount of heat is released because the hydration reaction of sulfuric acid is highly exothermic and dilution should always be performed by adding the acid to the water rather than the water to acid. As hydration of sulfuric acid is thermodynamically favorable and the affinity of it for water is sufficiently strong.

If you pour a few drops of petrol on your palm, it will feel cool as the petrol evaporates. This change a/an:

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. endothermic reaction

  2. exothermic reaction

  3. chemical reaction

  4. slow reaction

Show answer
Correct Option: A
Explanation:

If you pour a few drops of petrol on your palm.it will feel cool as the petrol evaporates this is a endothermic reaction.Because petrol is very volatile in nature, so when it evaporates.it absorb heat energy from the surroundings.

A chemical reaction in which energy is liberated is called:

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. exothermic reaction

  2. endothermic reaction

  3. isothermal reaction

  4. physical change

Show answer
Correct Option: A
Explanation:

Exothermic Reaction: This is a chemical reaction that releases energy through light or heat.

$CH _4+2O _2\rightarrow CO _2+2H _2O+\triangle$
Burning of $CH _4$ gas its produces $CO _2$ and water vapour and releases heat.
Endothermic Reaction: This is a chemical reaction which requires or absorbs energy from its surroundings usually in the form of heat.
$N _2+O _2\rightarrow 2NO$
$\triangle0=+180.5$kg

During the dissolution of urea, heat:

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. is absorbed

  2. is evolved

  3. does not change

  4. none of the above

Show answer
Correct Option: A
Explanation:

During the dissolution of urea, heat is absorbed the term,dissolution,refers to a solute dissolving in a solvent to form a solution.In this experiment the solute is  solid urea.Urea being a molecular substance,does not dissociate into ions.The dissolution process involves adding energy to break the attractive forces between the molecules in the solid structure and releasing energy as the molecules form new attractive forces with the water molecules sourrounding it.

One of the following is an exothermic reaction. This is:

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. electrolysis of water.

  2. conversion of limestone into quicklime.

  3. process of respiration.

  4. process of photosynthesis.

Show answer
Correct Option: C
Explanation:

(A)In electrolysis of water heat energy is used to convert water into hydrogen and oxygen.

$2H _2O\rightarrow2H _2+O _2$
 it is an endothermic reaction.

(B)conversion of limestone into quicklime can be done by heating limestone.
$CaCO _3\rightarrow CaO+CO _2$ it is an endothermic reaction.


(C)During respiration breakdown of glucose in presence of oxygen releases energy, therefore it is an exothermic process.
$C _6H _{12}O _6+6O _2\rightarrow6H _2O+6CO _2+energy$

(D)In process of photosynthesis- light energy is used to convert carbon dioxide and water into glucose and oxygen
$6CO _2+6H _2O\rightarrow C _6H _{12}O _6+6O _2$

So the answer is (c)






.

One of the following is an endothermic reaction. This is:

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. combination of carbon and oxygen to form carbon monoxide.

  2. combination of nitrogen and oxygen to form nitrogen monoxide

  3. combination of glucose and oxygen to form carbon dioxide and water

  4. combination of zinc and hydrochloric acid to form zinc chloride and hydrogen.

Show answer
Correct Option: B
Explanation:
(A) This is an incomplete combustion reaction so energy will be released.
(B)Combination of nitrogen and oxygen to form Nitrogen Monoxide-
Heat is required for this process.
So $N _2 + O _2\rightarrow2NO-180.6KJ$ is an endothermic reaction.
(C) combination of glucose and oxygen to form carbon dioxide and water is a combustion reaction.So energy will be released.
(D)in a combination of zinc and hydrochloric acid to form zinc chloride and hydrogen heat is released.

so correct answer is  (B).

The formation of a larger chemical from the smaller components is known as 

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. an endothermic reaction that requires energy

  2. an endothermic reaction that releases energy

  3. an exothermic reaction that requires energy

  4. an exothermic reaction that releases energy

  5. hydrolysis

Show answer
Correct Option: C
Explanation:

The internal energy of a larger chemical is smaller than that of the constituent ones. Hence energy is liberated when smaller components combine to form a large molecule. Hence the process is exothermic.

The correct answer is option D.

Which is a reaction that absorbs energy?

chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

  1. Exothermic

  2. Particle Size

  3. Endothermic

  4. Catalyst

  5. Concentration

Show answer
Correct Option: C
Explanation:

The term endothermic process describes the process or reaction in which the system absorbs energy from its surroundings; usually, in the form of heat. The opposite of an endothermic process is an exothermic process, one that releases, "gives out" energy in the form of heat.