Question 1

What is the electron configuration of Magnesium (Mg)?

Accepted Answer

Magnesium has atomic number 12, with the complete configuration 1s² 2s² 2p⁶ 3s², where the outermost electrons fill the s-orbital.

Question 2

In the p-block, which group contains elements that are generally non-metallic and form acidic oxides?

Accepted Answer

Group 15 (pnictogens: N, P, As, Sb, Bi) forms acidic oxides like N₂O₅ and P₂O₅ when combined with oxygen.

Question 3

In the reaction 2H₂ + O₂ → 2H₂O, how many moles of water are produced from 4 moles of hydrogen gas?

Accepted Answer

From the balanced equation, 2 moles of H₂ produce 2 moles of H₂O; therefore, 4 moles of H₂ produce 4 moles of H₂O.

Question 4

Which of the following elements belongs to the s-block of the periodic table?

Accepted Answer

Sodium is an alkali metal in Group 1 with its valence electron in the s-orbital, classifying it as an s-block element.

Question 5

When calcium (Ca) reacts with oxygen (O₂), the product formed is:

Accepted Answer

Calcium, an s-block alkaline earth metal with +2 oxidation state, combines with oxygen's -2 oxidation state to form CaO in a 1:1 molar ratio.

Question 6

Which p-block element forms a diatomic molecule and exhibits allotropy with forms like white, red, and black phosphorus?

Accepted Answer

Phosphorus exhibits multiple allotropic forms including white (P₄), red, and black phosphorus due to different structural arrangements.

Question 7

Which element belongs to Group 17 (Halogens) and Period 3?

Accepted Answer

Chlorine (Cl) is located at Group 17, Period 3 with electron configuration [Ne]3s²3p⁵.

Question 8

Which of the following is NOT an isotope of hydrogen?

Accepted Answer

Helium is a separate element (atomic number 2); protium, deuterium, and tritium are the three naturally occurring isotopes of hydrogen.

Question 9

Which position does hydrogen occupy in the periodic table?

Accepted Answer

Hydrogen is placed in Group 1 (alkali metals group) and Period 1 as the first element in the periodic table.

Question 10

What is the oxidation state of hydrogen in the compound H₂O₂ (hydrogen peroxide)?

Accepted Answer

In H₂O₂, oxygen has an oxidation state of -1 (peroxide ion), making hydrogen +1 to balance the molecule.

Question 11

Which property correctly describes the s-block elements?

Accepted Answer

s-block elements (alkali metals and alkaline earth metals) readily lose their valence s-electrons to form positively charged ions and ionic compounds.

Question 12

Which of the following represents the correct order of increasing atomic radius in the s-block?

Accepted Answer

Atomic radius increases down a group in the periodic table; Li (Group 1, Period 2) < Na (Period 3) < K (Period 4).

Question 13

Which of the following p-block elements has the highest electronegativity?

Accepted Answer

Fluorine is the most electronegative element on the periodic table with an electronegativity value of 4.0 on the Pauling scale.

Question 14

What is the electronic configuration of Boron (B), a p-block element?

Accepted Answer

Boron has atomic number 5 with configuration 1s² 2s² 2p¹, making it the first element in group 13 of the p-block.

Question 15

The element with the highest electronegativity value in the periodic table is:

Accepted Answer

Fluorine (F) has the highest electronegativity (3.98 on Pauling scale) due to its small size and high nuclear charge.

Question 16

Atomic radius generally increases down a group because:

Accepted Answer

Adding new electron shells as you move down a group increases atomic radius despite increasing nuclear charge.

Question 17

Which of the following elements is a transition metal with atomic number 26?

Accepted Answer

Iron has atomic number 26 and belongs to the d-block transition metals in Period 4.

Question 18

What is the atomic number of hydrogen?

Accepted Answer

Hydrogen is the lightest element with atomic number 1 and one proton.

Question 19

Which period of the periodic table contains the first lanthanide series element?

Accepted Answer

The lanthanides (4f-block) begin in Period 6 with Lanthanum (La, atomic number 57).

Question 20

Which of the following p-block elements is a noble gas with a complete octet configuration and zero electronegativity?

Accepted Answer

All noble gases (Ne, Ar, Kr, Xe, Rn) in group 18 have complete p-orbitals, full octets, and essentially zero electronegativity.

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