Explanation

• Stomata are tiny pores present mainly on the surface of leaves.
• They allow carbon dioxide (CO₂) to enter the plant for photosynthesis and release oxygen.
• Stomata are controlled by guard cells, which open and close the pores.

Last verified on 15-03-2026

Explanation

• The symbolic representation of a molecule of a compound is called a formula.
• It uses symbols and numbers to represent the composition of the molecule.
• For example, the formula for water is H₂O, indicating two hydrogen atoms and one oxygen atom.

Last verified on 15-03-2026

Explanation

• An atom is the smallest possible particle of an element that can combine to form new compounds.
• Atoms are the building blocks of matter, and they cannot be broken down into smaller particles.

Last verified on 15-03-2026

Explanation

• Valency is the combining capacity of an atom to form molecules or compounds.
• It depends on the number of electrons an atom can lose, gain, or share to complete its outer shell.

Last verified on 15-03-2026

Explanation

• Sound waves are mechanical waves that require a medium (air, water, or solid) to travel.
• They transport energy, not matter.
• Particles of the medium vibrate around their mean position but do not move along with the wave.
• Examples: Speaking, music, and alarms transfer energy through sound waves.

Last verified on 13-03-2026

Explanation

• Refraction: Bending of light when it passes from one medium to another.
• A prism bends light at different angles depending on wavelength.
• This separation of colors is called dispersion, forming a spectrum.
• Visible spectrum colors: Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV).

Last verified on 13-03-2026

Explanation

Thermal energy can be transferred through all three methods:

• Conduction: Direct transfer between particles in physical contact.
• Convection: Transfer through the movement of fluids.
• Radiation: Transfer through electromagnetic waves (e.g., light, radio waves).

Last verified on 13-03-2026

Explanation

• A molecule is the smallest particle of a substance that retains its chemical properties.
• It is made of two or more atoms chemically bonded together.
• Examples of molecules: H₂O, O₂, CO₂, NH₃, CH₄.

Additional information:

• An atom is the smallest unit of an element.
• A compound is a substance formed when different elements combine chemically.

Last verified on 13-03-2026

Explanation

• According to the Kinetic Molecular Theory, faster gas particles hit container walls more often.
• More frequent and stronger collisions increase the pressure.
• Higher temperature → higher particle speed → higher pressure.
• Pressure depends on number of collisions of gas molecules with container walls.
• Unit of gas pressure: Pascal (Pa).

Last verified on 13-03-2026

Explanation

• Freezing is the process by which a liquid changes to a solid.
• It is the reverse of melting, which is the process by which a solid changes to a liquid.

Last verified on 13-03-2026