Explanation

• Refrigerants are gases used in refrigerators to absorb heat and provide cooling.
• Freon (CFCs) and ammonia are commonly used in domestic and commercial refrigeration.
• They evaporate at low temperatures, absorbing heat from the fridge interior.
  

Last verified on 03-02-2026

Explanation

Rock salt is also known as halite.

It is the mineral form of sodium chloride (NaCl)

It is commonly used for de-icing roads and as table salt in cooking.

Explanation

Explanation

• A hydrometer is an instrument used to measure the specific gravity of liquids.
• It works based on the principle of buoyancy.
• It is widely used to test milk, alcohol, and battery acid.
• Commonly used in laboratories and industries.

Last verified on 30-01-2026

Explanation

• Urea fertilizer contains 46% nitrogen (N).
• Urea is a white crystalline solid.
• It is widely used as a fertilizer and animal feed additive.

Last verified on 31-01-2026

Explanation

• When AlCl₃ is heated, it dimerizes to Al₂Cl₆.
• In Al₂Cl₆, each Al atom shares electrons with a Cl atom from the other AlCl₃ unit, forming covalent coordinate (dative) bonds.

Additional information:

• Al₂Cl₆ exists as a dimer in the gas phase, which is electron-deficient and demonstrates Lewis acid behavior.

Last verified on 28-01-2026

Explanation

There are four fundamental states of matter: solid, liquid, gas and plasma

1. Solid: Fixed shape and volume; particles tightly packed.
2. Liquid: Fixed volume but takes container's shape; particles close but move.
3. Gas: No fixed shape or volume; particles far apart and move freely. 
4. Plasma: Ionized gas, found in stars, lightning; electrically charged.

Explanation

Steel cans are coated with tin to prevent rusting and corrosion.

Tin provides a protective layer between steel and the beverage.

This ensures the drink remains safe and hygienic.

Explanation

The chemical name for quartz is silicon dioxide

Chemical Formula: SiO₂

Composition: Silicon (Si) and Oxygen (O)

Structure: A framework of silicon-oxygen tetrahedra

Common Names: Silica, Rock Crystal (for the clear variety)

Explanation

Christiaan Huygens (1629–1695) proposed the wave theory of light.

He suggested that light travels in the form of waves, not particles.

Huygens’ principle explains how light waves propagate, reflect, and refract.

This theory challenged Newton’s particle theory of light.