Explanation

• The Moon is Earth’s only natural satellite.
• Diameter – 3,474 km
• Distance from Earth – 384,400 km
• Orbital period – 27.3 days
• Surface gravity – 1/6th of Earth
• First human landing – Apollo 11, 1969

Last verified on 18-03-2026

Explanation

• Ca is the chemical symbol for calcium.
• Calcium is a chemical element with atomic number 20.
• It is an alkaline earth metal belonging to Group 2 of the periodic table.
• Calcium is essential for strong bones and teeth.

Additional information:

• Na — Sodium
• K — Potassium
• Fe — Iron
• Cu — Copper
• Ag — Silver

Last verified on 10-10-2026

Explanation

• An ammeter is specifically designed to measure electric current.
• A multimeter can also measure current, voltage, and resistance.
• Electric current is measured in amperes (A).
• An ammeter is connected in series with the circuit to measure current.

Additional information:

• Voltmeter: Measures voltage.
• Ohmmeter: Measures resistance.

Last verified on 10-10-2026

Explanation

• Respiration is the chemical process in which energy is released from food.
• Cells break down glucose to release energy for various life activities.
• Aerobic respiration uses oxygen, while anaerobic respiration occurs without oxygen.
• The released energy is stored mainly in the form of ATP (adenosine triphosphate).

Additional information:

• Nutrition: Taking in and using food.
• Digestion: Breaking down food into simpler substances.

Last verified on 10-10-2026

Explanation

• The Earth's outermost layer is called the Crust.
• The crust is the thin, solid outer layer where humans, animals, and plants live.
• It is located above the mantle, outer core, and inner core.
• It is made mainly of rocks and minerals.

Additional information:

• Earth's Layers (Outer to Inner): Crust → Mantle → Outer Core → Inner Core
• Crust Thickness: About 5–70 km
• Mantle Thickness: About 2,900 km
• Outer Core Thickness: About 2,260 km
• Inner Core Radius: About 1,220 km

Last verified on 04-08-2026

Explanation

• Kilometers per second: ≈ 300,000 km/s
• Speed in vacuum: 299,792,458 m/s
• Approximate value: 3 × 10⁸ m/s
• Symbol: c
• Distance traveled in 1 second: About 300,000 km
• Light from the Sun takes about 8 minutes 20 seconds to reach the Earth.

Last verified on 16-05-2026

Explanation

• The human respiratory system exchanges oxygen and carbon dioxide between the body and the environment.
• Oxygen enters the blood through the alveoli in the lungs.
• Carbon dioxide moves from the blood into the alveoli and is expelled during exhalation.
• Oxygen is used by cells for cellular respiration and energy production.

Last verified on 10-10-2026

Explanation

• Mercury Symbol: Hg
• Atomic number: 80
• Melting point: -38.83 °C
• Atomic mass: 200.59 u

Last verified on 13-03-2026

Explanation

• Digestion is the process of breaking down large food particles into smaller, simpler substances.
• It enables the body to absorb nutrients from food.
• Digestion involves mechanical and chemical processes.
• The digestive system includes the mouth, stomach, and intestines.

Additional information:

• Absorption: Movement of digested nutrients into the blood or lymph.
• Assimilation: Use of absorbed nutrients by body cells.

Last verified on 10-10-2026

Explanation

• Mercury is the smallest planet in our solar system.
• Mercury with a diameter of 4,879 km (3031.67 mi).
• Its escape velocity is approximately 4.25 km/s.
• Nearest Planet to Sun.
• Fastest Planet.

Last verified on 23-06-2026