Boost MDCAT/ECAT scores with ChemZap Aptitude Booster! High-yield Inorganic Chemistry, Periodic Table memory tricks, solved MCQs & rapid revision tips

Welcome to Learn Chemistry by Inam Jazbi, your fastest hub for high-yield chemistry revision!

This post is specially designed for students preparing for the ChemZap Aptitude Test, focusing on a Rapid Recap of Inorganic Chemistry and the Periodic Table.

Inorganic Chemistry is full of trends, patterns, and exceptions—exactly what ChemZap loves to test. That’s why this guide includes the smartest shortcuts, periodic trends, colour codes, oxidation state clues, block-wise properties, and high-scoring concepts that appear again and again in aptitude tests.

Whether you struggle with atomic radius, ionization energy, electronegativity, group behaviours, d-block properties, or periodic trends, this fast recap will help you master everything in just a few minutes.

Get ready for a super-easy, super-fast, and super-scoring revision session — the ChemZap way!

Let’s begin your rapid transformation into an Inorganic Chemistry pro.

MDCAT Inorganic Chemistry

ECAT Chemistry Preparation

Periodic Table Revision

High-Yield Chemistry Notes

ChemZap Aptitude Booster

Learn Chemistry by Inam Jazbi

Chemistry Shortcuts for MDCAT

MDCAT Past Paper MCQs Inorganic

ECAT High Score Chemistry Tips

Chemistry Trends and Tricks

MDCAT Chemistry 2025 Preparation

Periodic Table memory techniques

Periodic Table

Classification of Elements

Metals → Left side of the periodic table; Electropositive elements with 1-3 valence electrons (except boron)

Non-metals → Right side of the periodic table; electronegative elements with 4-7 valence electrons

Metalloids → intermediate properties of metals and non-metals, Border the staircase line e.g. B, Si, Ge, As, Sb, Te

Noble gases → Elements with full outermost shell or complete octet or duplet.

Brief Summary of Terms used in periodic Table

Modern Periodic Law (Moseley, 1913): Properties of elements are periodic functions of their atomic numbers.”

Periodic Table → Tabular arrangement of elements in the increasing order of their atomic numbers

Group Number → Number of valence electrons (electrons in the outermost shell)

Period number → Total number of shells

Valence electrons → Number of electrons in the outermost shell or valence shell ranging 1 to 8.

Valency → Determined by outermost electrons.

Basis of Periodic table

(i) Increasing order of atomic number

(ii) Periodicity (repetition in chemical properties after definite intervals)

Composition or Structure of Long Form of Periodic Table

▶ 7 horizontal rows or periods (written in Arabic letters)

▶ 18 vertical columns or groups (8A groups and 8B groups or total 18 groups)

▶ 4 blocks (s, p, d, f)

→ s-block: Groups 1–2 (IA–IIA)

→ p-block: Groups 13–18 (IIIA–VIIIA)

→ d-block/transition metals: Groups 3–12 (IIIA–VIIIB, IB, IIB), Group B elements having four series

→ f-block/inner transition metals: Lanthanides (4f series) & actinides (5f series)

Formula of Periodic Table

Based on (n+ l) Rule: ns → (n−2)f → (n−1)d → np

For example

For n = 6, the sequence of orbital is: 6s → 4f → 5d → 6p

General Valence Shell configuration of Different Blocks and Groups of The Periodic Table

Representative elements → ns¹⁻² np¹⁻⁶

s-block → ns¹⁻²

All p-block elements → ns² np¹⁻⁶

Active p-block elements → ns² np¹to ns² np⁵OR ns² np¹⁻⁵

Non-active p-block elements → ns² np⁶

d-block → (n–1)d¹, ns² to (n–1)d¹⁰, ns² OR (n–1)d¹⁰, ns⁰⁻² OR (n–1)d¹⁰, ns¹⁻²

f-block → (n–2)f¹⁻¹⁴, (n–1)d¹, ns² OR (n–2)f²⁻¹⁴, (n–1)d⁰⁻¹, ns² and (n–2)f⁰⁻¹⁴, (n–1)d⁰⁻², ns²

Groups

⇨ Groups are the vertical columns of elements in the periodic table having identical valance shell configuration.

⇨ Periodicity of properties of elements gives rise to groups of the periodic table.

⇨ There are 18 vertical columns in the periodic table, so there are 18 groups which are numbered from 1 to 18.

⇨ formerly, there were eight groups (I to VIII) but each group is further sub-divided into A and B sub-groups. But the total groups including A and B sub-groups are 16 as group VIIIB consists of three columns.

⇨ Groups are numbered by Roman numericals as IA, IIA, IIIB to VIIIB (comprising of three columns), IB, IIB, IIIA to VIIIA or zero group (or by simple Arabic numericals as 1, 2, 3, ……….. 16, 17, 18).

⇨relationship between the two ways of numbering the groups

⇨ The elements of sub-group A or the elements of groups 1, 2, 13, 14, 15, 16, 17, and 18 are called Main group or Normal or Major or Representative Elements.

⇨ The elements of sub-group B (groups 3 t 12) are called Transition (or outer transition) elements.

⇨ Group IA and IIA or group 1 to 2 = s-block (which include active metals)

⇨ Group IIIB and IIB or group 3 to 12 = d-block

⇨ Group IIIA and VIIIA or group 13 to 18 = p-block (which include all non-metals, metalloids & weak metals)

⇨ All f-block elements belongs to group IIIB.

⇨ IIIB group is the largest group of periodic table

⇨ Total 32 elements in IIIB group (4 d-block and 28 f-block elements)

General Characteristics of Groups

⇨ Representation of Total Valence Electrons

⇨ Representation of Maximum Valency and the highest Oxidation State

⇨ Exhibition of Identical Valence Shell Electronic Configuration

⇨ Exhibition of Same Chemical Properties

⇨ Exhibition of Regular Gradation in Physical Properties

⇨ Different Behaviour of First Congeners of Each Group

⇨ Increasing Electropositivity and Decreasing Electronegativity

⇨ Identical valence orbital on descending a group

⇨ Difference in Properties of Sub-groups A and B

⇨ Representative and Transition elements

Summary of General Properties of Group IA, IIA, VIIA and Group VIIIA

Summary of General Properties of Group IIIA, IVA, VA and Group VIA

Periods

▶ Period number indicates ‘n’ for outermost shell or the total number of shells.

▶ Each period starts from s-block (alkali metal, except period 1)) and ends at p-block (noble gas).

▶ Constant number of shell and increasing number of valence electrons.

▶ Each period begins with new energy level.

▶ Increasing valency with respect to hydrogen from 1 to 4 and then falling from 3 to 1.

▶Different chemical properties due to different valence shell configuration.

▶ Variation in properties of elements change from metallic to non-metallic.

▶ Placement of metals are at far left side and non-metals at the right side of table.

▶Increasing Metallic character and decreasing non-metallic character increases across each period.

▶ Decreasing Atomic volume or atomic radius (i.e. size of atom) across each period.

▶ The number of elements in each period is twice the number of atomic orbitals available.

First period (two element)

H (s-block)

He (p-block, placed in p-block due to stable configuration of noble gases)

2^nd and 3^rd period

Total 8 elements each

Two s-block elements and six p-block elements

4^th and 5^th periods

▶ 18 elements each

▶ 8 representative elements

▶ 10 outer transition elements

6^th period

▶ 32 elements each

▶ 8 representative elements

▶ 10 outer transition elements

▶14 inner transition elements (Lanthanides, rare earth elements)

Blocks of Periodic Table on the Basis of the Subshell of the Valence shell of element

Representative Elements/ Main group or Normal or Major Elements

Definition: These elements have completely filled inner shells, but their outermost shell is incomplete with less than 8 valence electrons.

Group Placement

Group: Belong to Group IA to VIIIA (i.e., subgroup A or Groups 1, 2, 13–18).

Location: Located on the left and right sides of the periodic table.

Block Classification

⇨ Include elements of the s-block and p-block.

⇨ s-block: Groups 1–2 (alkali and alkaline earth metals).

⇨ p-block: Groups 13–18 (includes metals, metalloids, and nonmetals).

General Valence Shell Configuration:

ns¹¯² to ns² np¹¯⁵ (ns¹¯² to np¹¯⁶)

Element Types

Metals: Groups IA, IIA, and some of IIIA (Al, Ga, In, Tl), Miscellaneous metals: Sn, Pb, Bi, Po.

Nonmetals: Found mostly in upper right (C, N, O, F, P, S, Cl, etc.).

Metalloids: B, Si, Ge, As, Sb, Te, Po (and sometimes At).

Composition and Distribution

Total Representative Elements: 42 (including noble gases)

Metals: 20 (12 s-block + 8 p-block)

Nonmetals: 14 (N₂, O₂, F₂, Cl₂, Br₂, I₂, C, P, S, Ne, Ar, Kr, Xe, Rn)

Metalloids: 8 (B, Si, Ge, As, Sb, Te, Po, At)

Physical States

Solids: 31 (19 metals, 4 nonmetals, 8 metalloids)

Liquids: 2 (Ga and Br₂)

Gases: 9 (mainly nonmetals and noble gases)

Transition Elements

Definition: partially filled d or f-orbitals in their atoms or ions in their atomic state or ionized state

Group Placement: Elements of Subgroup B (or the elements of groups 3 t 12)

Block Classification: d and f-block elements

General Valence Shell Configuration:

(n−1)d^1-10, ns^1-2 (except Pd) or (n−1)d^1-10, ns^0-2 valence shell configuration for d-block

(n−2)f^2-14, (n−1)d^0-2, ns² valence shell configuration for f-block

Outer Transition Elements or d-Block Elements

1. The elements of sub-group B or the elements of groups 3 t 12 having

2. partially filled d-orbitals in their atoms or ions in which last electron enters into (n–1)d-orbitals in their atomic state or ionized state

3. two outermost shells are incomplete i.e. outermost valence shell (s-subshell) penultimate shell (d-subshell)

4. placed in the middle of periodic table between s & p-block elements

5. (n−1)d^1-10, ns^1-2 (except Pd) or (n-1)d^1-10, ns^0-2 valence shell configuration (where, n = 4, 5, 6, 7).

6. They all are metals characterized by their high melting and boiling points, variable valencies and oxidation states, catalytic property, forming coloured paramagnetic compounds (Except zinc, cadmium, mercury) and their ability to form complex ions by co-ordination through co-ordinate covalent bonds.

7. They form acidic, basic & amphoteric oxides. Acidic nature of oxides increases with increasing oxidation state

8. The outer transition (d-block) elements consist of following 4 series of 10 elements each:

Inner Transition Elements or f-Block Elements

1. These elements in which the filling of electrons takes place in the inner (n–2)f-orbitals (4f or 5f sub-shell).

2. partially filled f-orbitals (except ₇₁Lu, ₉₀Th, ₁₀₃Lr) in their atoms or ions in which last electron enters into (n–2)f-orbitals in their atomic state or ionized state

3. three outermost shells are incomplete i.e. outermost valence shell (i.e. ns-subshell) and (n–1)d-subshell, penultimate f-subshell or (n–2)f-orbitals.

4. Properly they should be placed after IIIB but these elements are found in a separate position at the bottom of the periodic table.

5. General valence shell electronic configuration of Inner Transition elements

(n–2)f^2-14, (n–1)d^0-1, ns²and (n–2)f^0-14, (n–1)d^0-2, ns²OR

(n–2)f^2-14/0-14, (n–1)d^0-1/0-2, ns² (where n = 6-7)

6. f-block consists of two series of 14 elements each namely Lanthanide Series and Actinide Series. Lanthanides and actinides are collectively known as inner transition elements.

Lanthanides/4f series in 6th period; following 57La and it is from 58Ce to 71Lu

Actinides/5f series in 7th period; following 89Ac and it is from 90Th to 103Lr

Rules for Identification of Group, Period and Block of Elements in the Periodic Table

Prediction of Period

The period of an element corresponds to the principal quantum number of the valence shell.

Prediction of Block

The block of an element corresponds to the type of valence orbital or highest energy orbital (out of s, p, d and f) of the valence shell which receives the last electron.

Prediction of Group

The group of an element is equal to the total number of electrons in the valence shell or and penultimate shell (i.e. total number of valence electrons). Group number depends on block:

(a) For s-block elements, group number is equal to the number of valence electrons in s-orbital.

(b) For p-block elements, group number is equal to the number of electrons in ‘s’ and ‘p-orbitals’ (or 10 + number of valence electrons in the valence shell or 12 + number of “p” electrons in the valence shell).

(d) For f-block elements; group number is always 3 or III (or no group).

Prediction of Block of Elements in the Peroidic Table

The block of elements in the periodic table can be predicted from its group number as:

▶ Group 1 to 2 → s-block

▶ Group 3 to 12 → p-block

▶ Group 13 to 18 → d-block

Some Important Elements and their Physical characteristics

List of Cations with their symbols or formulae

[Note: All cations are simple radical except few which are shown italic in the chart. Anions may be simple or compound radical. If they are simple they have suffix ide and if they are compound they have suffix ate or ite except few which are shown italic in chart]

List of Anions with their symbols or formulae

Electronic Configuration of first 38 Elements

Order of filling: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 5d¹, 4f, 5d, 6p, 7s, 6d¹, 5f, 6d, 7p

Electronic Configuration of Cations and Anions

[*Note: While writing E.C. of transition metal cations, electrons are first removed from ns orbital and after that removal of electrons takes place from (n–1)d orbital].

Values of Some Important Periodic Properties of Elements

Elements with no Isotopes or Monoisotopic Elements

Nearly all elements found in nature are mixture of several isotopes. Out of 92 natural elements, only 23 elements have no isotopes, each consisting of only one kind of atom. The remaining 69 natural elements have from 2 to 10 isotopes.

Solubility Chart

Activity Series or Reactivity Series

1. A list of metals arranged in order of increasing ease of oxidation is called an activity series. It ranks the elements in order of their reducing ability in aqueous solution.

2. It is a convenient summary of the results of many possible metal or hydrogen displacement reactions. This series is based on metal-acid reaction and metal compound-metal reaction. According to this series, any metal above hydrogen will displace it from water or from an acid, but metals below hydrogen will not react with either water or an acid. [In fact, any species listed in the series will react with a compound containing any species listed below it].

3. The metals at the top are most readily oxidized and are stronger reducing agents whereas the metals at the bottom of the series are less readily oxidized and are weaker reducing agents.

Natural Abundance of Elements in Earth’s Crust in % by Mass

[Oxygen abundance is 50% which means that in a 100 g sample of Earth’s crust, there are 50 g of the element O.]

Natural Abundance of Elements in Human Body

General Physical Properties of Acids and Bases

Group Trend / Periodic Trend of Physical Properties in Periodic Table

Composition and Uses of Important Alloys of Metals

Composition and Uses of Important Alloys of Copper / Zinc

Composition and Uses of Important Alloys of Aluminium

Composition and Uses of Important Alloys of Lead

Composition and Uses of Important Alloys of Iron

Composition and Uses of Important Alloys of Gold

Common silicates, their formulae and uses

List of Important Acids and Bases

Important salts and hydrates and their formulae Set I

Important salts and hydrates and their formulae Set II

Important hydrates and their formulae Set III

Important Complexes and their formulae

Important Organic Compounds and their formulae

Ores of Different Elements (S, Mg, Ca, Na, K, Fe, Cu, Zn, Pb, Al and Si)

Ores of Sulphur

Ores of Magnesium and Calcium

Ores of Sodium and Potassium

Ores of Zinc and Lead

Ores of Iron and Copper

Important Oxides and their Formulae

ChemZap Aptitude Booster – High-Yield MCQs & Quizzes

💡 Topic 1: Periodic Table Trends

Q1: Which element has the highest electronegativity?
🟦 A) Oxygen
🟩 B) Fluorine ✅
🟥 C) Sodium
🟨 D) Calcium
Answer: B) Fluorine — It has the highest electronegativity in the periodic table.

Q2: Atomic size increases down a group because:
🟦 A) Electrons are removed
🟩 B) Number of electron shells increases ✅
🟥 C) Nuclear charge decreases
🟨 D) Electronegativity increases
Answer: B) More electron shells make the atom larger.

Q3: Ionization energy generally decreases down a group because:
🟦 A) Electrons are closer to nucleus
🟩 B) Electron shielding increases ✅
🟥 C) Nuclear charge decreases
🟨 D) Atomic number decreases
Answer: B) Shielding reduces the effective nuclear pull.

Q4: Which element is least metallic?
🟦 A) Lithium
🟩 B) Fluorine ✅
🟥 C) Calcium
🟨 D) Sodium
Answer: B) Fluorine — Non-metallic, highly electronegative.

💡 Topic 2: Oxidation States

Q5: Common oxidation state of Zn in ZnSO₄?
🟦 A) +1
🟩 B) +2 ✅
🟥 C) +3
🟨 D) +4
Answer: B) +2

Q6: Common oxidation state of Cu in CuSO₄?
🟦 A) +1
🟩 B) +2 ✅
🟥 C) +3
🟨 D) 0
Answer: B) +2

Q7: Which element shows variable oxidation states?
🟦 A) Sodium
🟩 B) Iron ✅
🟥 C) Magnesium
🟨 D) Calcium
Answer: B) Iron — +2, +3 are common.

Q8: Oxidation state of S in H₂SO₄?
🟦 A) +2
🟩 B) +4
🟥 C) +6 ✅
🟨 D) -2
Answer: C) +6

💡 Topic 3: Hydrates & Compounds

Q9: ZnSO₄·7H₂O is commonly called?
🟦 A) White Vitriol ✅
🟩 B) Blue Vitriol
🟥 C) Red Vitriol
🟨 D) Green Vitriol
Answer: A) White Vitriol

Q10: CuSO₄·5H₂O is called:
🟦 A) White Vitriol
🟩 B) Blue Vitriol ✅
🟥 C) Green Vitriol
🟨 D) Red Vitriol
Answer: B) Blue Vitriol

Q11: Which salt is anhydrous?
🟦 A) Na₂CO₃·10H₂O
🟩 B) CuSO₄ ✅
🟥 C) ZnSO₄·7H₂O
🟨 D) MgSO₄·7H₂O
Answer: B) CuSO₄ (dry, no water molecules)

Q12: ZnSO₄·10H₂O is called?
🟦 A) White Vitriol
🟩 B) Zinc Sulphate Decahydrate ✅
🟥 C) Blue Vitriol
🟨 D) Magnesium Sulphate
Answer: B) Zinc Sulphate Decahydrate

💡 Topic 4: Solubility & Precipitation

Q13: Which salt is soluble in water?
🟦 A) AgCl
🟩 B) NaCl ✅
🟥 C) BaSO₄
🟨 D) PbSO₄
Answer: B) NaCl — All sodium salts are soluble.

Q14: Which salt is insoluble in water?
🟦 A) KNO₃
🟩 B) BaSO₄ ✅
🟥 C) Na₂SO₄
🟨 D) NH₄Cl
Answer: B) BaSO₄ — Very low solubility.

Q15: Precipitate formed when AgNO₃ reacts with NaCl?
🟦 A) NaNO₃
🟩 B) AgCl ✅
🟥 C) AgNO₃
🟨 D) NaCl
Answer: B) AgCl — Insoluble white precipitate.

💡 Topic 5: Acid-Base Strength

Q16: Strong acid among the following?
🟦 A) HCl ✅
🟩 B) HF
🟥 C) CH₃COOH
🟨 D) H₂CO₃
Answer: A) HCl

Q17: Weak base among the following?
🟦 A) NaOH
🟩 B) NH₃ ✅
🟥 C) KOH
🟨 D) Ba(OH)₂
Answer: B) NH₃

Q18: Conjugate base of HCl?
🟦 A) H⁺
🟩 B) Cl⁻ ✅
🟥 C) OH⁻
🟨 D) H₂O
Answer: B) Cl⁻

Q19: Strongest acid in water?
🟦 A) H₂SO₄ ✅
🟩 B) HClO
🟥 C) HNO₂
🟨 D) CH₃COOH
Answer: A) H₂SO₄

Q20: Which salt solution is neutral?
🟦 A) NaCl ✅
🟩 B) NH₄Cl
🟥 C) Na₂CO₃
🟨 D) KOH
Answer: A) NaCl — Neutral salt of strong acid & strong base.

Periodic Table Interactive Quiz – Test Your Chemistry Knowledge!

1️⃣ Which element is a liquid at room temperature?

🔹 A) Mercury
🔹 B) Gold
🔹 C) Chlorine
🔹 D) Sodium
Answer: Mercury
Explanation: Mercury (Hg) is the only metal that is liquid at room temperature.

2️⃣ Which group contains the most reactive metals?

🔹 A) Alkali Metals
🔹 B) Noble Gases
🔹 C) Halogens
🔹 D) Transition Metals
Answer: Alkali Metals
Explanation: Alkali metals (Group 1) are highly reactive, especially with water.

3️⃣ Noble gases are known for being:

🔹 A) Very reactive
🔹 B) Colorful
🔹 C) Inert
🔹 D) Magnetic
Answer: Inert
Explanation: Noble gases have full outer electron shells, making them mostly unreactive.

4️⃣ Which element has the highest electronegativity?

🔹 A) Oxygen
🔹 B) Fluorine
🔹 C) Carbon
🔹 D) Nitrogen
Answer: Fluorine
Explanation: Fluorine is the most electronegative element on the Periodic Table.

5️⃣ Which element is essential for life and found in all proteins?

🔹 A) Nitrogen
🔹 B) Helium
🔹 C) Calcium
🔹 D) Argon
Answer: Nitrogen
Explanation: Nitrogen is a key component of amino acids and proteins.

6️⃣ Which element is commonly used in lightbulbs?

🔹 A) Neon
🔹 B) Tungsten
🔹 C) Sodium
🔹 D) Copper
Answer: Tungsten
Explanation: Tungsten has a high melting point and is ideal for filament in lightbulbs.

7️⃣ Which element forms table salt when combined with sodium?

🔹 A) Fluorine
🔹 B) Chlorine
🔹 C) Oxygen
🔹 D) Iodine
Answer: Chlorine
Explanation: Sodium chloride (NaCl) is common table salt.

8️⃣ Which element has the symbol 'K'?

🔹 A) Krypton
🔹 B) Potassium
🔹 C) Calcium
🔹 D) Gold
Answer: Potassium
Explanation: The symbol 'K' comes from the Latin name kalium.

9️⃣ Which element is used in balloons because it’s lighter than air?

🔹 A) Hydrogen
🔹 B) Helium
🔹 C) Neon
🔹 D) Argon
Answer: Helium
Explanation: Helium is safe and lighter than air, so it lifts balloons.

🔟 Which element is in Group 17 (Halogens)?

🔹 A) Fluorine
🔹 B) Neon
🔹 C) Sodium
🔹 D) Magnesium
Answer: Fluorine
Explanation: Halogens include F, Cl, Br, I, and At.

1️⃣1️⃣ Which element is most abundant in the Earth’s crust?

🔹 A) Oxygen
🔹 B) Iron
🔹 C) Silicon
🔹 D) Aluminum
Answer: Oxygen
Explanation: Oxygen makes up about 46% of Earth’s crust by weight.

1️⃣2️⃣ Which element is used in nuclear reactors as fuel?

🔹 A) Uranium
🔹 B) Thorium
🔹 C) Plutonium
🔹 D) All of the above
Answer: All of the above
Explanation: Uranium, thorium, and plutonium can be used as nuclear fuels.

1️⃣3️⃣ Which element has the symbol 'Ag'?

🔹 A) Gold
🔹 B) Silver
🔹 C) Argon
🔹 D) Arsenic
Answer: Silver
Explanation: 'Ag' comes from the Latin word argentum.

1️⃣4️⃣ Which element is a gas at room temperature and essential for respiration?

🔹 A) Carbon
🔹 B) Oxygen
🔹 C) Nitrogen
🔹 D) Hydrogen
Answer: Oxygen
Explanation: Oxygen is vital for breathing and cellular respiration.

1️⃣5️⃣ Which element is used in pencils?

🔹 A) Lead
🔹 B) Graphite
🔹 C) Carbon
🔹 D) Both B & C
Answer: Both B & C
Explanation: Pencil “lead” is actually graphite, which is a form of carbon.

1️⃣6️⃣ Which element is a halogen that is a liquid at room temperature?

🔹 A) Fluorine
🔹 B) Chlorine
🔹 C) Bromine
🔹 D) Iodine
Answer: Bromine
Explanation: Bromine is the only halogen that is liquid at room temperature.

1️⃣7️⃣ Which element is used in batteries?

🔹 A) Lithium
🔹 B) Sodium
🔹 C) Potassium
🔹 D) Calcium
Answer: Lithium
Explanation: Lithium-ion batteries are widely used in electronics.

1️⃣8️⃣ Which element’s symbol is 'Fe'?

🔹 A) Fluorine
🔹 B) Iron
🔹 C) Francium
🔹 D) Fermium
Answer: Iron
Explanation: 'Fe' comes from the Latin word ferrum.

1️⃣9️⃣ Which element is used in making stainless steel?

🔹 A) Chromium
🔹 B) Nickel
🔹 C) Iron
🔹 D) All of the above
Answer: All of the above
Explanation: Stainless steel is an alloy of iron, chromium, and nickel.