Class 10 Science Chapter 5 MCQ

Metallic character increases down a group and decreases along a period. Thus, metallic character increases in the order Be, Mg, Ca as they belong to same group.

Its outermost shell has 4 electrons. So, it is a non-metal. Non-metal forms acidic oxide and by sharing of electrons with halogen, it forms covalent halide. Note: Atomic number 14 has electronic configuration 2, 8, 4.

If two (or more) elements have the same number of valence electrons, then they belong to the same group of the periodic table. For example, if two elements have electronic configurations of 2, 8, 1 and 2, 8, 8, 1, then they have the same number of valence electrons (1 valence electron each), and hence they belong to the same group of the periodic table.

The first period starts with hydrogen and ends with noble gas helium. All other periods start with alkali metals like lithium, sodium, potassium, etc., and end with noble gases like neon, argon, krypton, etc.

All the elements of a group of the periodic table have the same number of valence electrons. e.g., all the elements of group 1 have one valence electron each in their atoms. All the elements of group 18 have 8 valence electrons each in their atoms, except helium which has only 2 valence electrons in its atom. All the remaining three properties increase down the group. Note: On moving down in a particular group of the periodic table, the number of valence electrons in the elements remains the same. All the remaining three properties increase down the group.

Here, all the statements are correct. Hence, your answer will be option [D].

Element with electronic configuration 2, 8, is an inert gas i.e., neon and hence, belongs to group 18. Note: Group 18 elements are known as noble gases or inert gases. They are helium, neon, argon, krypton etc. All the noble gases have 8 electrons in their outermost shell (except helium which has only 2 electrons) in the K valence shell. Thus, the valence shells of all the noble gases are completely filled with electrons.

Here, all the statements are correct. Hence, your answer will be option [D].

All the elements in the modern periodic table are arranged on the basis of their increasing atomic number. All the isotopes can be placed at one place in the same group of the periodic table. Note: In the modern periodic table or in the long form of the periodic table, the elements are arranged in increasing order of their atomic numbers. This table was prepared by Bohr and is based upon the electronic configuration of elements.

The groups 1 and 2, and 13 to 17 contain the normal elements (typical elements or representative elements). Group 18 elements are known as noble gases or inert gases. They are helium, neon, argon, krypton, etc. All the noble gases have 8 electrons in their outermost shells (except helium which has only 2 electrons in the K valence shell). Thus, the valence shells of all the noble gases are completely filled with electrons.