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(i –c), 

(ii – a), 

(iii – b), 

(iv – d)

(i – c), 

(ii – a), 

(iii – d), 

(iv – b)

(i – d), 

(ii – c), 

(iii – b), 

(iv – a)

i. The elements of the s-block and p-block (except the group 18 or zero group elements) are called normal elements i.e. elements from groups 1, 2 and 13 to 17. 

ii. In the atoms of these elements only the outermost shell is incomplete. 

iii. Alkali metals, alkaline earth metals and halogens are some of the normal elements.

i. Elements present in groups 3 to 12 in the middle of the periodic table are called transition elements. 

ii. Their two outermost shells are incomplete.

iii. These elements are also called d-block elements. 

iv. All these elements are solid metals at room temperature (except mercury).

i. Elements present in group 18 on the extreme right of the modern periodic table are called inert elements or noble gases. They have completed outermost shell. 

ii. Their outermost shell contains 8 electrons except Helium which contains 2 electrons. 

iii. These elements do not gain or lose or share electrons with other atoms and hence, do not undergo any chemical reactions under ordinary conditions. 

iv. Their valency is zero. 

v. Hence, they are also called zero group elements. 

vi. These elements are included in ‘p’- block of modern periodic table. 

vii. Inert elements include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and Radon (Rn). 

viii. All these elements are gases.

(i – d), 

(ii – b), 

(iii – a)

(i – b), 

(ii – a), 

(iii – c), 

(iv – d)

(i – c), 

(ii – a), 

(iii – d), 

(iv – b)

i. Elements placed at the bottom of the periodic table are called inner transition elements. 

ii. They include two series of elements: lanthanides and actinides and are also called as f-block elements. 

iii. 14 elements with atomic numbers 58 to 71 (Ce to Lu) are called Lanthanides. These elements are placed along with lanthanum (La = 57) in group 3 and period 6 because of very close resemblance in properties between them. 

iv. 14 elements with atomic numbers 90 to 103 (Th to Lr) are called Actinides. These elements are placed along with actinium (Ac = 89) in group 3 and period 7 because of very close resemblance in their properties. 

v. They have three incomplete outermost shells. 

vi. All these elements are metals.

(i – c), 

(ii – a), 

(iii – b)

Potassium: Others are metalloids.

i. The 18^th column of modern periodic table is known as zero group or group 18.

ii. Four elements of zero group are Helium (He), Neon (Ne), Argon (Ar) and Krypton (Kr).

iii. Zero group elements (or inert gases or noble elements) have stable electronic configuration with complete duplet (in the case of He) or complete octet (in the case of Ne, Ar, etc). 

iv. Due to this, the valency of these elements is zero. 

v. As their valencies are satisfied, these elements do not lose, gain or share electrons with other atoms and therefore, they do not take part in the chemical reactions under ordinary conditions. Hence, zero group elements or inert gases are chemically inert.

i. Mendeleev found that the chemical and physical properties of elements showed repetition after certain intervals. 

ii. He arranged all the known elements in a tabular form in the increasing order of their atomic masses in horizontal rows till he encountered an element which had properties similar to the first element. 

iii. He placed this element below the first element and thus started the second row of elements. 

iv. Proceeding in this manner he could arrange all the 63 elements known till then according to their properties and thus created the first periodic table.

The metals, non metals and metalloids among the first twenty elements of the modern periodic table are as follows: Metals: Lithium (Li), Berylium (Be), Sodium (Na), Magnesium (Mg), Aluminium (Al), Potassium (K), Calcium (Ca) 

Non-metals: Hydrogen (H), Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F), Phosphorus (P), Sulphur (S), Chlorine (Cl) 

Metalloids: Boron (B), Silicon (Si)

Copper: Others are normal elements, while copper is a transition element.

True

Hydrogen resembles alkali metals as well as halogens

False: 

f-block elements are placed at the bottom of the periodic table.

Silicon, Germanium

Elements of group 1 (or I A) are called alkali metals

Copper, Zinc

There are 18 groups in the modern periodic table.

Phosphorus, Sulphur

Carbon, Nitrogen

There are seven periods in the modern periodic table.

Magnesium, Calcium

Lithium, Sodium

Mendeleev’s periodic law was modified into modern periodic law.

Shortest period (first) contains two elements and long periods (fourth and fifth) contain eighteen elements each.

Non-metals are said to be Electronegative.

Eight electrons are present in the outermost orbit of inert elements, except helium which has two electrons in the outermost orbit.

Dobereiner’s classification of elements was not useful because he could identify only some triads from the known elements, as other triads did not obey Dobereiner’s rule.

i. If inert elements lose one of the outermost electrons, they will no longer be inert. They will acquire an electron to become stable again. 

ii. If the atomic size of metals decreases, the electrostatic force of attraction between the nucleus and the outermost electrons will increase as the distance between them decreases. Thus, it will be difficult for the metal atom to lose its outermost electron. Hence, their metallic character will decrease. 

iii. If the maximum capacity of outermost shell of an atom becomes seven, then the eighth electron in the outermost shell of an inert gas (excluding He) will shift to the next shell. Thus, the inert gases will no longer be inert and new set of elements (halogens) will have stable electronic configuration.

When Newlands arranged the elements in an increasing order of their atomic masses, he found that every eighth element had properties similar to that of the first.

All isotopes of the same elements have different masses but same atomic number.

False: 

Newlands arranged all the elements in an increasing order of their atomic masses.

Correct answer is (A) atomic masses

i. Metallic character is the tendency of an atom to lose electrons. 

ii. In a period, electrons are added to the same shell and hence, these electrons experience greater pull from the nucleus. Thus, atomic size decreases. 

iii. It becomes difficult to remove an electron from the atom. 

Hence, metallic character decreases from left to right in a period.

Correct answer is (C) p-block

i. Formation of molecules is based on the electronic configuration of the combining elements. 

ii. In the case of inert gases, all the shells, including the outermost shell, are completely filled. 

iii. They have stable electronic configuration with complete duplet (in case of He) or complete octet (in case of Ne, Ar, etc). 

iv. Due to this stable electronic configuration, atoms of these elements do not lose, gain or share electrons with other atoms. 

Hence, inert gases exist in the form of free atoms.

Non-metals show tendency to accept or share electrons with other atoms.

Correct answer is (B) decreases from left to right

Correct answer is (B) actinides

i. X has atomic number 17 i.e. Cl and its electronic configuration is (2,8,7). Thus, its valency is 1. Y has atomic number 20 i.e. Ca and its electronic configuration is (2,8,8,2). Thus, its valency is 2. 

∴ The compound will be YX2 i.e. CaCl2 

ii. X accepts electron, therefore, it is a nonmetal; Y donates electrons, so it is a metal. 

iii. Y has valency 2 and oxygen also has valency 2. 

∴ Formula of oxide of Y is YO i.e. CaO.

i. The number of electrons in the outermost shell of an atom is its valence electrons. Valency is determined by the number of valence electrons present in the outermost shell of an atom. 

ii. The number of valence electrons for all the elements in a group is the same. 

So, elements in the same group show same valency.