Why do we need to classify elements - 1
1
According to the basic concept of chemistry, elements are considered to be the basic units of:
Practice
A
Only compounds
B
Only mixtures
C
All types of matter
D
Only living organisms
✅ Show Answer
✔ Correct Answer:
C
(All types of matter)
💡 Explanation
Element: Dictionary meaning — a pure substance consisting of only one type of atom and having a definite atomic number.
Explanation — Elements are the fundamental substances from which all other substances are formed. Each element is made up of atoms having the same number of protons.
Basic unit: Dictionary meaning — the fundamental or smallest component that forms a larger structure.
Explanation — Elements are regarded as basic units because matter is made up of elements, either as individual elements or as combinations of elements in compounds and mixtures.
Matter: Dictionary meaning — anything that has mass and occupies space.
Explanation — Matter includes substances such as elements, compounds, and mixtures. Elements serve as the fundamental building blocks of matter.
Given Statement - The elements are the basic units of all types of matter.
Explanation — Elements are the fundamental substances from which all other substances are formed. Each element is made up of atoms having the same number of protons.
Basic unit: Dictionary meaning — the fundamental or smallest component that forms a larger structure.
Explanation — Elements are regarded as basic units because matter is made up of elements, either as individual elements or as combinations of elements in compounds and mixtures.
Matter: Dictionary meaning — anything that has mass and occupies space.
Explanation — Matter includes substances such as elements, compounds, and mixtures. Elements serve as the fundamental building blocks of matter.
Given Statement - The elements are the basic units of all types of matter.
🎯 Conclusion
Elements are the basic units of all types of matter. They may exist independently or combine with other elements to form compounds and mixtures.
2
How many elements were known in the year 1800?
Practice
A
21
B
31
C
41
D
51
✅ Show Answer
✔ Correct Answer:
B
(31)
💡 Explanation
Known elements: Dictionary meaning — elements that had been discovered and identified by scientists at a particular time.
Explanation — The number of known elements increased gradually as scientists discovered and identified new elements. In the year 1800, only 31 elements were known.
Element: Dictionary meaning — a pure substance consisting of atoms with the same atomic number.
Explanation — An element contains only one type of atom based on its number of protons. Different elements have different atomic numbers.
Year 1800: Dictionary meaning — the year marking the beginning of the nineteenth century.
Explanation — At this time, the scientific knowledge of elements was much more limited than today. Only 31 elements had been discovered and recognized.
Given Statement - In 1800, only 31 elements were known.
Explanation — The number of known elements increased gradually as scientists discovered and identified new elements. In the year 1800, only 31 elements were known.
Element: Dictionary meaning — a pure substance consisting of atoms with the same atomic number.
Explanation — An element contains only one type of atom based on its number of protons. Different elements have different atomic numbers.
Year 1800: Dictionary meaning — the year marking the beginning of the nineteenth century.
Explanation — At this time, the scientific knowledge of elements was much more limited than today. Only 31 elements had been discovered and recognized.
Given Statement - In 1800, only 31 elements were known.
🎯 Conclusion
In 1800, only 31 elements were known. The number of known elements increased significantly as new elements were discovered over time.
3
By 1865, how many elements had been identified?
Practice
A
31
B
43
C
63
D
73
✅ Show Answer
✔ Correct Answer:
C
(63)
💡 Explanation
Identified elements: Dictionary meaning — elements that have been discovered, recognized, and established as distinct chemical substances.
Explanation — As scientific methods improved, more elements were discovered and identified. By the year 1865, the number of identified elements had increased to 63.
Doubled: Dictionary meaning — increased to twice the original amount.
Explanation — In 1800, 31 elements were known. More than doubling this number means increasing it to more than 62. By 1865, 63 elements had been identified, which was slightly more than double the 1800 number.
Element: Dictionary meaning — a pure substance consisting of atoms having the same atomic number.
Explanation — Each element is characterized by its atomic number, which is equal to the number of protons present in the nucleus of its atoms.
By 1865: Dictionary meaning — at or before the specified time in the year 1865.
Explanation — The statement indicates that by the year 1865, scientists had identified 63 elements.
Given Statement - By 1865, the number of identified elements had more than doubled to 63.
Explanation — As scientific methods improved, more elements were discovered and identified. By the year 1865, the number of identified elements had increased to 63.
Doubled: Dictionary meaning — increased to twice the original amount.
Explanation — In 1800, 31 elements were known. More than doubling this number means increasing it to more than 62. By 1865, 63 elements had been identified, which was slightly more than double the 1800 number.
Element: Dictionary meaning — a pure substance consisting of atoms having the same atomic number.
Explanation — Each element is characterized by its atomic number, which is equal to the number of protons present in the nucleus of its atoms.
By 1865: Dictionary meaning — at or before the specified time in the year 1865.
Explanation — The statement indicates that by the year 1865, scientists had identified 63 elements.
Given Statement - By 1865, the number of identified elements had more than doubled to 63.
🎯 Conclusion
By 1865, the number of identified elements had increased to 63, which was more than double the 31 elements known in 1800.
4
According to the given statement, how many elements are known at present?
Practice
A
104
B
110
C
114
D
118
✅ Show Answer
✔ Correct Answer:
C
(114)
💡 Explanation
Present: Dictionary meaning — the current time or the time being discussed.
Explanation — In the given statement, 'at present' refers to the time at which the statement is being considered.
Element: Dictionary meaning — a pure substance consisting of atoms having the same atomic number.
Explanation — An element is a fundamental substance that cannot be broken down into simpler substances by ordinary chemical methods.
Known: Dictionary meaning — discovered, identified, or recognized as existing.
Explanation — When an element is said to be known, it means that it has been discovered and scientifically identified.
Given Statement - At present 114 elements are known.
Explanation — In the given statement, 'at present' refers to the time at which the statement is being considered.
Element: Dictionary meaning — a pure substance consisting of atoms having the same atomic number.
Explanation — An element is a fundamental substance that cannot be broken down into simpler substances by ordinary chemical methods.
Known: Dictionary meaning — discovered, identified, or recognized as existing.
Explanation — When an element is said to be known, it means that it has been discovered and scientifically identified.
Given Statement - At present 114 elements are known.
🎯 Conclusion
According to the given statement, 114 elements are known at present.
5
According to the given statement, the recently discovered elements are mainly:
Practice
A
Naturally occurring elements
B
Man-made elements
C
Non-metallic elements
D
Noble gases
✅ Show Answer
✔ Correct Answer:
B
(Man-made elements)
💡 Explanation
Recently discovered: Dictionary meaning — discovered or identified in a relatively recent period of time.
Explanation — The phrase 'recently discovered elements' refers to elements that were identified more recently compared with elements known from earlier periods.
Man-made: Dictionary meaning — produced or created artificially by humans rather than occurring naturally.
Explanation — Some recently discovered elements are produced artificially by scientists through nuclear reactions. They are therefore described as man-made or synthetic elements.
Element: Dictionary meaning — a pure substance consisting of atoms having the same atomic number.
Explanation — Elements are characterized by their atomic numbers and cannot be converted into simpler substances by ordinary chemical methods.
Synthetic: Dictionary meaning — made artificially rather than obtained directly from nature.
Explanation — Synthetic elements are produced by humans, usually through nuclear reactions, rather than being obtained as naturally occurring substances.
Given Statement - Of the known elements, the recently discovered elements are man-made.
Explanation — The phrase 'recently discovered elements' refers to elements that were identified more recently compared with elements known from earlier periods.
Man-made: Dictionary meaning — produced or created artificially by humans rather than occurring naturally.
Explanation — Some recently discovered elements are produced artificially by scientists through nuclear reactions. They are therefore described as man-made or synthetic elements.
Element: Dictionary meaning — a pure substance consisting of atoms having the same atomic number.
Explanation — Elements are characterized by their atomic numbers and cannot be converted into simpler substances by ordinary chemical methods.
Synthetic: Dictionary meaning — made artificially rather than obtained directly from nature.
Explanation — Synthetic elements are produced by humans, usually through nuclear reactions, rather than being obtained as naturally occurring substances.
Given Statement - Of the known elements, the recently discovered elements are man-made.
🎯 Conclusion
The recently discovered elements referred to in the statement are man-made or synthetic elements, produced artificially by scientists.
6
What does the statement "Efforts to synthesise new elements are continuing" indicate?
Practice
A
No new elements can be produced
B
Scientists are continuing attempts to produce new elements
C
All elements have already been discovered naturally
D
Only naturally occurring elements are being studied
✅ Show Answer
✔ Correct Answer:
B
(Scientists are continuing attempts to produce new elements)
💡 Explanation
Efforts: Dictionary meaning — attempts or activities made to achieve a particular goal.
Explanation — In this statement, 'efforts' refers to the scientific attempts being made to produce or discover new elements.
Synthesise: Dictionary meaning — to produce or create a substance by combining or using appropriate processes.
Explanation — In chemistry, synthesising a new element means producing it artificially, usually through nuclear reactions involving existing atomic nuclei.
New elements: Dictionary meaning — elements that have not previously been produced or identified.
Explanation — Scientists can attempt to create new elements by carrying out carefully controlled nuclear reactions. Such elements may have very high atomic numbers and can often be highly unstable.
Continuing: Dictionary meaning — still happening or being carried on without stopping.
Explanation — The word 'continuing' indicates that scientific research and attempts to produce new elements are still in progress.
Given Statement - Efforts to synthesise new elements are continuing.
Explanation — In this statement, 'efforts' refers to the scientific attempts being made to produce or discover new elements.
Synthesise: Dictionary meaning — to produce or create a substance by combining or using appropriate processes.
Explanation — In chemistry, synthesising a new element means producing it artificially, usually through nuclear reactions involving existing atomic nuclei.
New elements: Dictionary meaning — elements that have not previously been produced or identified.
Explanation — Scientists can attempt to create new elements by carrying out carefully controlled nuclear reactions. Such elements may have very high atomic numbers and can often be highly unstable.
Continuing: Dictionary meaning — still happening or being carried on without stopping.
Explanation — The word 'continuing' indicates that scientific research and attempts to produce new elements are still in progress.
Given Statement - Efforts to synthesise new elements are continuing.
🎯 Conclusion
Scientists are continuing their efforts to synthesise new elements, mainly through controlled nuclear reactions and advanced experimental techniques.
7
Why is it difficult to study the chemistry of all elements and their compounds individually?
Practice
A
Because only a few elements form compounds
B
Because the number of elements and their compounds is very large
C
Because all elements have identical chemical properties
D
Because elements cannot undergo chemical reactions
✅ Show Answer
✔ Correct Answer:
B
(Because the number of elements and their compounds is very large)
💡 Explanation
Individually: Dictionary meaning — separately, one at a time, or considered as a single unit.
Explanation — Studying elements individually would require examining the properties and chemical behaviour of each element separately, along with the many compounds it forms.
Chemistry: Dictionary meaning — the branch of science concerned with the composition, structure, properties, and reactions of substances.
Explanation — The chemistry of an element includes its physical and chemical properties, reactions, compounds, and behaviour under different conditions.
Compounds: Dictionary meaning — pure substances formed when two or more different elements combine chemically in definite proportions.
Explanation — Elements can combine with one another to form a very large number of compounds. Studying every compound separately would therefore be extremely difficult.
Innumerable: Dictionary meaning — too many to be counted or extremely numerous.
Explanation — The word 'innumerable' emphasizes that the number of compounds formed by the known elements is extremely large.
Given Statement - With such a large number of elements, it is very difficult to study individually the chemistry of all these elements and their innumerable compounds.
Explanation — Studying elements individually would require examining the properties and chemical behaviour of each element separately, along with the many compounds it forms.
Chemistry: Dictionary meaning — the branch of science concerned with the composition, structure, properties, and reactions of substances.
Explanation — The chemistry of an element includes its physical and chemical properties, reactions, compounds, and behaviour under different conditions.
Compounds: Dictionary meaning — pure substances formed when two or more different elements combine chemically in definite proportions.
Explanation — Elements can combine with one another to form a very large number of compounds. Studying every compound separately would therefore be extremely difficult.
Innumerable: Dictionary meaning — too many to be counted or extremely numerous.
Explanation — The word 'innumerable' emphasizes that the number of compounds formed by the known elements is extremely large.
Given Statement - With such a large number of elements, it is very difficult to study individually the chemistry of all these elements and their innumerable compounds.
🎯 Conclusion
It is difficult to study every element and its compounds individually because there are many known elements and an extremely large number of compounds formed by them.
8
Why did scientists classify the elements?
Practice
A
To increase the number of elements
B
To make the study of elements and their properties easier
C
To change elements into compounds
D
To eliminate the need for experiments
✅ Show Answer
✔ Correct Answer:
B
(To make the study of elements and their properties easier)
💡 Explanation
Classifying: Dictionary meaning — arranging things into groups according to their common characteristics or properties.
Explanation — Scientists classified elements by grouping them systematically based on similarities and differences in their properties. This made the large amount of chemical information easier to study and understand.
Systematic: Dictionary meaning — done according to a planned, organized, and logical method.
Explanation — A systematic classification arranges elements according to definite rules or patterns rather than randomly. This helps scientists identify relationships between different elements.
Organise: Dictionary meaning — to arrange or structure information or objects in an orderly manner.
Explanation — By organizing elements into groups, scientists could study elements with similar properties together instead of studying every element separately.
Knowledge: Dictionary meaning — information and understanding gained through study, observation, or experience.
Explanation — Scientists had accumulated a large amount of information about the properties and behaviour of elements. Classification provided a convenient way to organize this knowledge.
Given Statement - Scientists searched for a systematic way to organise their knowledge by classifying the elements.
Explanation — Scientists classified elements by grouping them systematically based on similarities and differences in their properties. This made the large amount of chemical information easier to study and understand.
Systematic: Dictionary meaning — done according to a planned, organized, and logical method.
Explanation — A systematic classification arranges elements according to definite rules or patterns rather than randomly. This helps scientists identify relationships between different elements.
Organise: Dictionary meaning — to arrange or structure information or objects in an orderly manner.
Explanation — By organizing elements into groups, scientists could study elements with similar properties together instead of studying every element separately.
Knowledge: Dictionary meaning — information and understanding gained through study, observation, or experience.
Explanation — Scientists had accumulated a large amount of information about the properties and behaviour of elements. Classification provided a convenient way to organize this knowledge.
Given Statement - Scientists searched for a systematic way to organise their knowledge by classifying the elements.
🎯 Conclusion
Scientists classified elements to organize their growing chemical knowledge systematically and to make the study of elements and their properties easier.
9
What was one important advantage of systematically classifying the elements?
Practice
A
It could only increase the number of known elements
B
It could rationalize known chemical facts and predict new ones
C
It could convert all elements into compounds
D
It could eliminate the need for further study
✅ Show Answer
✔ Correct Answer:
B
(It could rationalize known chemical facts and predict new ones)
💡 Explanation
Rationalize: Dictionary meaning — to explain or organize facts in a logical and systematic way.
Explanation — Classification of elements helped scientists organize and explain the known chemical facts about elements in a logical manner. It made relationships between elements easier to understand.
Chemical facts: Dictionary meaning — established information about the chemical properties and behaviour of substances.
Explanation — Chemical facts include properties such as reactivity, valency, atomic size, and the types of compounds formed by elements.
Predict: Dictionary meaning — to state or estimate what is likely to happen or be discovered in the future based on available information.
Explanation — A good system of classification does more than organize existing knowledge. It can also indicate the properties of elements that have not yet been discovered.
Undertaking: Dictionary meaning — beginning or carrying out a particular task or activity.
Explanation — The prediction of new elements and their properties provided scientists with directions for further investigation and study.
Given Statement - Classification of elements could rationalize known chemical facts and predict new ones for further study.
Explanation — Classification of elements helped scientists organize and explain the known chemical facts about elements in a logical manner. It made relationships between elements easier to understand.
Chemical facts: Dictionary meaning — established information about the chemical properties and behaviour of substances.
Explanation — Chemical facts include properties such as reactivity, valency, atomic size, and the types of compounds formed by elements.
Predict: Dictionary meaning — to state or estimate what is likely to happen or be discovered in the future based on available information.
Explanation — A good system of classification does more than organize existing knowledge. It can also indicate the properties of elements that have not yet been discovered.
Undertaking: Dictionary meaning — beginning or carrying out a particular task or activity.
Explanation — The prediction of new elements and their properties provided scientists with directions for further investigation and study.
Given Statement - Classification of elements could rationalize known chemical facts and predict new ones for further study.
🎯 Conclusion
Systematic classification of elements helped scientists organize and rationalize known chemical facts and also predict the existence and properties of new elements for further study.