Explanation

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

The hardest substance in the world is diamond.

Its hardness is due to the strong covalent bonding between its carbon atoms.

This making it the most resistant to scratching.

Category: Native minerals

Cleavage: 111 (perfect in four directions)

Crystal class: Hexoctahedral (m3m); H-M symbol: (4/m 3 2/m)

Crystal habit: Octahedral

Crystal system: Cubic

Dana classification: 1.3.6.1

Density: 3.5–3.53 g/cm3 3500–3530 kg/m3

Explanation

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

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

Explanation

As this diagram shows, pH ranges from 0 to 14, with 7 being neutral.

pH less than 7 are acidic.

pH greater than 7 are alkaline.

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

Diamond is an allotropic form of carbon.

Carbon is capable of forming many allotropes, which are structurally different forms of the same element, due to its valency.

Some of the well-known forms of carbon include:

• Diamond
• Graphite
• Graphene
• Lonsdaleite (hexagonal diamond)
• Graphenylene
• Carbophene
• AA'-graphite
• Diamane
• Amorphous carbon
• Nanocarbons
• Glassy carbon
• Carbon nanofoam
• Carbide-derived carbon
• Linear acetylenic carbon
• Cyclocarbons

Explanation

An atomic bomb is based on the nuclear reaction known as nuclear fission,

A heavy atomic nucleus splits into two or more lighter nuclei, releasing a large amount of energy in an uncontrolled chain reaction.

The bombs dropped on Hiroshima and Nagasaki were examples of nuclear fission bombs, utilizing uranium-235 or plutonium-239 as the fissionable material. 

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