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

What are transition elements?

  1. The elements having 2 outermost shells incomplete.

  2. The elements having 3 outermost shells incomplete.

  3. The elements having the outermost shell full.

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Yes, it is correct, they have the 2 outermost shells incomplete and valence electrons are available from them. They are also called d block elements.The three long periods 4th ,5th,6th periods come in this.

Multiple choice

Why some gaps are seen in Mendeleev's periodic table?

  1. He predicted the existence of some elements and space was left for them.

  2. It showed gaps between the atomic weight of elements in a continuous manner.

  3. Space was left for isotopes and nobel gases.

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is correct because Mendeleev was able to predict the existence and even properties of some elements and so he left space for them in the periodic table.

Multiple choice

Which period is incomplete in the periodic table?

  1. First period

  2. Second period

  3. Seventh period

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is correct. It starts with element Francium. This period contains the heaviest element which occurs naturally on earth, uranium. Most of the subsequent elements in this period have been synthesized artificially and on many  elements of this period work is still going on in the lab.  All elements are radioactive in this period.

Multiple choice

Which of the following statements is/are incorrect?

(a). Atoms of most elements are able to exist independently. (b). Atoms form molecules and ions. (c). An atom is a group of molecules tightly held together by attractive forces.

  1. (a) only

  2. (b) only

  3. (c) only

  4. (a) and (b)

  5. (a) and (c)
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct answer as both these statements are incorrect. Atoms of most elements are not able to exist independently. A molecule is, in general, a group of two or more atoms that are chemically bonded together, i.e. tightly held together by attractive forces.

Multiple choice

Which of the following is / are true regarding the properties of elements in a group? (a) Electropositive character increases, moving from top to bottom. (b) Atomic radius decreases, moving from top to bottom. (c) Valence electrons increase, moving from top to bottom. (d) Number of shells remains the same moving from top to bottom.

  1. only a

  2. both a and b

  3. both b and c

  4. both c and d

  5. a, b and c
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Yes, it is correct. Only a is correct. Atomic radius increases, the number of valence electrons remains the same and the number of shells increase, while moving from top to bottom in a group.

Multiple choice

How many valence electrons are there in C (Carbon)?

  1. 4

  2. 5

  3. 2

  4. 8
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carbon has 4 valence electrons in its outermost shell, which allows it to form 4 covalent bonds with other atoms. This property makes carbon the foundation of organic chemistry.

Multiple choice

'He' is the symbol of

  1. helium

  2. hydrogen

  3. water

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

In the periodic table, 'He' is the chemical symbol for helium, a noble gas. Hydrogen's symbol is 'H', oxygen is 'O', and water is H2O (a compound, not an element with a single symbol).

Multiple choice

No two electrons in the atom can have the same set of quantum numbers known as

  1. Hund' s rule

  2. Pauli exclusion principle

  3. Bohr' s rule

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

The Pauli Exclusion Principle states that no two electrons in an atom can have identical sets of four quantum numbers (n, l, ml, ms). This explains electron arrangement in orbitals and the structure of the periodic table. Hund's rule deals with electron pairing in degenerate orbitals. Bohr's model is about electron orbits. Heisenberg's principle is about position-momentum uncertainty.

Multiple choice

Which of the following sets represents ferromagnetic elements?

  1. Fe, Co, Zn

  2. Fe, Co, Ni

  3. Ti, Fe, Ni

  4. Co, Ni, Cu

  5. Sc, Tl, Fe
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, the substances which are strongly attracted by magnetic field and show permanent magnetism even in the absence of a magnetic field are ferromagnetic. For example: Fe, Co, Ni, etc.

Multiple choice

The newly discovered “Super heavy” element 112 in periodic table has been named as

  1. copernicium

  2. germanibium

  3. upacbium

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Element 112 (copernicium, Cn) was officially named in 2009 after Nicolaus Copernicus, the astronomer who proposed the heliocentric model. It was first synthesized in 1996 at the GSI Helmholtz Centre for Heavy Ion Research in Germany. The name honors Copernicus' revolutionary contribution to our understanding of the solar system.