Assertion (A): Properties of a compound are different from those of its constituent elements.
Reason (R): Compounds are formed by chemical combination of elements in a fixed ratio.
Understanding Compound Properties and Formation
This question asks us to evaluate two statements about compounds and their constituent elements.
Analysis of Assertion (A)
Assertion (A): Properties of a compound are different from those of its constituent elements.
This statement is true. When elements combine chemically to form a compound, the resulting substance has completely new and distinct properties that are unrelated to the properties of the individual elements that make it up. A classic example is the formation of sodium chloride (table salt).
- Sodium (Na): A highly reactive, silvery metal that explodes in water.
- Chlorine (Cl): A poisonous, greenish-yellow gas.
- Sodium Chloride (NaCl): A white, crystalline solid essential for life and used as table salt.
Clearly, the properties of sodium chloride are vastly different from those of sodium and chlorine.
Analysis of Reason (R)
Reason (R): Compounds are formed by chemical combination of elements in a fixed ratio.
This statement is also true. Compounds are formed when atoms of different elements bond together chemically. This process follows specific laws, such as the Law of Definite Proportions, which states that a given chemical compound always contains its component elements in fixed, definite proportions by mass, regardless of the source or method of preparation. For example, water (H2O) always consists of hydrogen and oxygen atoms bonded in a 2:1 ratio.
Connecting Assertion (A) and Reason (R)
Reason (R) provides the fundamental explanation for why Assertion (A) is true. The chemical combination of elements, occurring in a fixed ratio as described in Reason (R), involves the formation of new chemical bonds. This process fundamentally alters the electronic structure and arrangement of the atoms, leading to the creation of a new substance with unique physical and chemical properties that differ significantly from the original constituent elements.
Therefore, the fact that compounds are formed through a specific chemical process involving a fixed ratio (R) directly explains why the resulting compound's properties are different from its constituent elements (A).
Conclusion
Both Assertion (A) and Reason (R) are true statements. Furthermore, Reason (R) serves as the correct explanation for Assertion (A).
Important Questions from Assertion and Reasons (Notes)
- Given below are two arguments.
(I): A valid deductive argument that also has all true premises is called a sound argument
(II): A strong inductive argument that has all true premises is called a cogent argument
In the light of the above statements, choose the most appropriate answer from the options given below - Given below are two statements one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A A sample survey is usually extensive in scope
Reason R Therfore, both in the number of cases included and in the manner of their selection, it has to be adequately and faithfully representative of a larger population. - Select the option that is true regarding the following two statements labelled Assertion (A) and Reason (R).
Assertion (A): A rubber band is a solid because it regains its original shape when the stretching force is removed.
Reason (R): Solids are rigid and have negligible compressibility. - Which of the following statements are correct?
(i) Solid $CO_2$ is called dry ice.
(ii) Solid $CO_2$ changes directly into gas at 1 atm pressure.
(iii) Pressure and temperature can change the state of matter.
(iv) Solid $CO_2$ melts into liquid $CO_2$ before becoming gas. - Select the option that is true regarding the following two statements labelled Assertion (A) and Reason (R).
Assertion (A): Copper wire in iron sulphate solution shows no visible reaction.
Reason (R): Copper is less reactive than iron.
