Explanation

1. Oxygen: The most abundant element in the Earth's crust, making up about 47% of the Earth's mass.
2. Silicon: The second most abundant element in the Earth's crust, making up about 27.7% of the crust 
3. Aluminum: The third most abundant element in the Earth's crust, making up around 8.1%.

Explanation

Ethyl alcohol, or ethanol, is commonly used in perfumes as a base solvent.

It helps dissolve fragrance oils and allows the scent to disperse evenly when applied.

Explanation

In Karst topography, both gypsum and dolomite are soluble.

They can form karst landscapes through dissolution.

This process is similar to limestone, though it occurs at varying rates.

Explanation

The process of applying a zinc coating to iron or steel to prevent rusting is called galvanizing.

This helps protect the metal from corrosion.

Explanation

Oxy-acetylene welding is a very common welding process.

Gases used in welding and cutting processes include:

• shielding gases such as carbon dioxide, argon, helium, etc.
• fuel gases such as acetylene, propane, butane, etc.

oxygen, used with fuel gases and also in small amounts in some shielding gas mixtures

Explanation

Electrons are lost in an oxidation reaction.

Oxidation simply means a gain of oxygen and an oxidizing agent is a substance that oxidizes something.

The reduction is the gain of electrons

Explanation

Hydrogen has an atomic weight of 1.00794u and accounts for 75% of the universe,

Thus making it the lightest and most abundant element in the universe.

Explanation

Bromine is the only non-metal that remains in liquid form at room temperature.

It is a reddish-brown liquid with a strong odor and is highly reactive.

Explanation

The ability of metals to be drawn into thin wires is known as ductility.

This property allows metals to be stretched without breaking.

This making them useful in various applications.

Explanation

It's measured by Young's modulus (modulus of elasticity) — the higher the Young's modulus, the stiffer and more elastic (in the sense of resisting deformation) the material.

• Copper: ~110–130 GPa
• Silver: ~80–83 GPa
• Iron: ~190–210 GPa
• Quartz (fused silica): ~70–75 GPa

Last updated 24-07-2026 by NA