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 outer ear (pinna and ear canal) collects sound vibrations from the environment.
• These vibrations travel through the auditory canal to the eardrum (tympanic membrane).

Additional information:

Main Parts of the Ear

• Outer Ear – Pinna and auditory canal
• Middle Ear – Eardrum and three ossicles (malleus, incus, stapes)
• Inner Ear – Cochlea and semicircular canals (hearing and balance)

Last verified on 15-03-2026

Explanation

• Nitrogen (N2) makes up about 78% of the Earth's atmosphere.
• Making it the most abundant gas in the atmosphere.
• It is followed by oxygen (~21%), with other gases in much smaller amounts.

Last verified on 15-03-2026

Explanation

The atomic number (proton number) determines the element.

Both X (₁₉) and Y (₁₉) have the same proton number 19, so they represent the same element but different isotopes.

• ⁴⁰₁₉X → Proton number = 19, Mass number = 40
• ³⁹₁₉Y → Proton number = 19, Mass number = 39
• ³⁸₂₀Z → Proton number = 20, Mass number = 38

Last verified on 15-03-2026

Explanation

• Phosphorus molecule naturally exists as P₄.
• It means one molecule contains four phosphorus atoms bonded together.
• This form is commonly found in white phosphorus, where the atoms form a tetrahedral structure.

Additional information:

• O₂ – Oxygen molecule
• N₂ – Nitrogen molecule
• H₂ – Hydrogen molecule
• Cl₂ – Chlorine molecule

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