Explanation

Gold has the symbol Au.

It has the atomic number 79.

This making it one of the higher atomic number elements found in nature.

Explanation

Iron is the most used metal in construction, machinery, and tools.

Its alloy, steel, is the backbone of modern industry.

Explanation

Diamond and graphite are two allotropes of carbon:

As allotropes, they are different structural forms of the same element, carbon, which exhibit distinct physical properties due to their unique atomic arrangements

Explanation

Lead is commonly used as a shield against gamma rays.

Due to its high density.

It effectively absorbs and blocks gamma radiation.

Explanation

Limestone is a Sedimentary Rock, Stratified Rock, Aqueous Rock.

Limestone consists of calcium carbonate,

Which has the chemical formula CaCO3.

Calcium carbonate is a chemical compound

It is a common substance found in rocks as the minerals calcite

RK11-12-22

Explanation

Argon is a commonly used gas used to fill incandescent light bulbs.

It increases bulb life by preventing the tungsten filaments from deteriorating too quickly.

Other gases are also used in lighting such as:

• Helium
• Neon
• Nitrogen
• Krypton

Explanation

A lock is a device used for raising and lowering boats,

ships and other watercraft between stretches of water of different levels on river and canal waterways.

Explanation

The two most common elements in the Earth's crust are:

• Oxygen (O) – about 46.6% by weight
• Silicon (Si) – about 27.7% by weight

Together, they form most of the silicate minerals, which make up the majority of the crust. 

Last updated 14-feb-2026

Explanation

Explanation

The elements of the periodic table sorted by atomic number

Atomic number Name chemical element                 Symbol

1                         Hydrogen                                             H

2                         Helium                                                     He

3                         Lithium                                                      Li

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RY 15-01-2023