Chemistry

Periodic Classification and Elements

1,176 Questions

Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.

Periodic table structureAtomic orbitalsElement identificationPeriodic laws

Periodic Classification and Elements Questions

Multiple choice

Which of the following statements regarding an element is false?

  1. Elements combine randomly to form a compound.

  2. Elements are represented by symbols.

  3. The atoms of an element are different from atoms of other elements.

  4. The number of atoms present in a molecule of an element is known as the atomicity of the element.

  5. A compound can be split into simpler substances or elements.

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

No, elements combine in fixed proportion by mass to form a compound.

Multiple choice

Which of the following statements is incorrect for an element?

  1. It cannot be converted into anything simpler.

  2. Each element consists of only one kind of atom.

  3. It exists as an individual atom or a molecule.

  4. Different elements are composed of the same atoms.

  5. Different elements are composed of the different atoms.

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Different elements are composed of different atoms.

Multiple choice

The element ‘Eka-aluminium’ predicted by Mendeleev is

  1. gallium

  2. boron

  3. germanium

  4. silicon
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mendeleev left some blank spaces in the periodic table for those elements, which were not known at that time. He had predicted that these elements would be discovered later on. He even had predicted the properties of these elements in the light of other elements present in the same group. Mendeleev named these elements by prefixing the Sanskrit word ‘Eka’ to the name of preceding element in the same group, i.e. Eka–boron for scandium, Eka–aluminium for gallium and Eka–silicon for germanium.

Multiple choice

Which of the following observations posed a challenge to Mendeleev’s periodic law?

(a) Position of alkali metals (b) Position of isotopes (c) Anomalies of atomic weights and properties of elements (d) Placing of dissimilar elements in the same group

  1. Only (a)

  2. Only (b), (c) and (d)

  3. Only (b) and (c)

  4. Only (c) and (d)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mendeleev, in his periodic table, arranged the elements according to their increasing atomic masses but gave priority to the similarity in the fomulas of the oxides and hydrides while groupig them. As a result at some places, an element with a greater atomic mass was placed before an element with a lower atomic mass. For example, Co (atomic mass = 58.93 u) was placed before Ni (atomic mass = 58.71 u), which challenged the law that Mendleeev gave, that the properties of elements are periodic funtions of their atomic masses. Moreover the isotopes of an element have different atomic masses, but could not be alloted separate places in the periodic table on account of the similarity in the formulas their oxides and hydrides.  Therefore, (c) and (d) posed a challenge to Mendeleev's periodic law.

Multiple choice

Which of the following are the discrepancies in Mendeleev's periodic table?

(a) He placed some alkali metals with coinage metals in the same group. (b) He placed dissimilar elements in the same group. (c) The atomic masses do not increase in a regular manner in going from one element to the next in the same period.

  1. Only (a) and (b)

  2. Only (a), (b) and (c)

  3. Only (a) and (c)

  4. Only (b) and (c)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

All the statements given above were the discrepancies in Mendeleev's periodic table.