Explanation

Explanation

• Gas molecules move freely in all directions because the particles are far apart.
• Gas particles have weak intermolecular forces and high kinetic energy.

Additional information:

• Solids: Vibrate in fixed positions
• Liquids: Move/slide around each other

Last verified on 06-10-2026

Explanation

• Hepta- is the prefix used to represent 7 carbon atoms.
• It is derived from the Greek word hepta, meaning seven.

Additional information:

• 1 = Mono-
• 2 = Di-
• 3 = Tri-
• 4 = Tetra-
• 5 = Penta-

Last verified on 06-10-2026

Explanation

• Polyethylene (PE) is one of the most widely used plastics in the world.
• Because it is lightweight, durable, chemically resistant, and relatively inexpensive.
• It is commonly used to make plastic bags, bottles, containers, packaging films, and household products.
• Polyethylene is produced from ethylene (ethene) through polymerization.

Last verified on 05-10-2026

Explanation

• Nitrous oxide, commonly known as laughing gas.
• It is a colorless, non-flammable gas used in medicine.
• Nitrous oxide (N₂O) causes temporary laughing and relaxation.

Additional information:

• Nitrous oxide was discovered by Joseph Priestley in 1772.

Last verified on 18-01-2026

Explanation

• The smallest unit of matter is an atom.

Structure of an Atom

• Nucleus: The central part made of heavy protons and neutrons.
• Electrons: Tiny, light particles that circle the nucleus.
• Protons: Particles with a positive charge.
• Neutrons: Particles with no electrical charge

Explanation

• Hydrogen and helium are the two lightest gases.
• Helium is the second most abundant element in the universe, after hydrogen.
• Helium has monatomic molecules.
• It is the lightest of all gases except hydrogen.
• Hydrogen is the lightest gas known.
• It provides the maximum lift for balloons due to its very low density.

Last updated question 17-02-2026

Explanation

• Carbon dioxide (CO₂) is used in fire extinguishers.
• It extinguishes fire by displacing oxygen and cooling the burning material.
• CO₂ fire extinguishers are especially effective for electrical and flammable liquid fires.
• Carbon dioxide is a colorless and non-flammable gas.
• It leaves no residue after use.

Explanation

• Marie Curie is the only person to win Nobel Prizes in two different natural sciences.
• She won the Nobel Prize in Physics in 1903.
• She won the Nobel Prize in Chemistry in 1911.
• She was awarded for her pioneering work on radioactivity.

Last verified on 06-09-2026

Explanation

• Aldehydes give a silver mirror test with Tollens' reagent.
• Tollens' reagent contains the diamminesilver(I) ion, [Ag(NH₃)₂]⁺.
• The aldehyde is oxidized to a carboxylic acid/carboxylate, while Ag⁺ is reduced to metallic silver.
• The deposited silver forms a shiny silver mirror on the test tube.

Last verified on 05-09-2026