Explanation

• Kinetic energy is the energy an object possesses due to its motion.
• Any moving object, such as a car, a ball, or a person, has kinetic energy.
• The amount of kinetic energy an object has depends on its mass and velocity.

Last verified on 18-03-2026

Explanation

• A saturated solution contains the maximum amount of solute that can dissolve at a given temperature.
• Any additional solute added will remain undissolved.
• Example: Sugar in water at room temperature reaches saturation when no more sugar dissolves.
• If a solution contains less solute than the maximum, it is called unsaturated.

Last verified on 18-03-2026

Explanation

• Nitrogen (N₂) makes up about 78% of Earth's atmosphere.
• It is a colorless, odorless, and inert gas, essential for life but not directly used in respiration.
  

Additional information:

Composition of Air – Approximate %:

• Nitrogen – 78%
• Oxygen – 21%
• Argon – 0.93%
• Carbon Dioxide – 0.04%
• Other trace gases (Neon, Helium, Methane, Krypton, etc.) – 0.03%

Last verified on 18-03-2026

Explanation

NOTE: Hydrogen is the lightest gas, but Helium is generally preferred. However, since "Helium" is not listed among your choices, the correct answer from the provided options is Hydrogen

• Helium is the lightest safe gas commonly used for:
• Party balloons
• Advertisement balloons
• Weather balloons

Common MCQ Confusion

• Hydrogen is actually the lightest gas overall, but it is highly flammable and can catch fire.
• Helium is slightly heavier than hydrogen but is non-flammable and safe, so it is used in balloons.

Last verified on 18-03-2026

Explanation

• Crystallization (or recrystallization) is the primary technique used for the purification of solid compounds

Important points:

• It is used to remove impurities from solid substances.
• The impure solid is dissolved in a suitable solvent, then crystals of the pure compound form on cooling.
• It is commonly used in organic chemistry for the purification of solids.

Last verified on 18-03-2026

Explanation

• A mixture contains two or more substances physically combined, which can be separated by physical means.
• Examples include sharbat, tea, steel.
• Common salt (NaCl) is a pure compound, not a mixture.

Last verified on 18-03-2026

Explanation

• Animal cells do not have chloroplasts, as they are not capable of photosynthesis.
• Animal cells also do not have a cell wall, unlike plant cells and some other organisms.

The components of an animal cell:

• Cell Membrane
• Cytoplasm
• Small Vacuole
• Nucleus
• Chromosomes

Last verified on 18-03-2026

Explanation

• Chromosomes are structures that carry genetic material (DNA) in cells.
• In animal cells, chromosomes are located in the nucleus, which controls cell activities and heredity.
• Number of chromosomes in humans: 46 (23 pairs)

Last verified on 18-03-2026

Explanation

Sum of 5 numbers = 5 × 12 = 60

Sum of 4 numbers = 4 × 13 = 52

Fifth number = 60 - 52 = 8

Last verified on 18-03-202

Explanation

Let the ages be x, x+4, x+8

Sum = x + (x+4) + (x+8) = 42

3x + 12 = 42

3x = 30

x = 10

Age of youngest child = 10

Last verified on 18-03-2026