Explanation

• Noble gases like helium, neon, and argon are placed in Group VIII (Group 18 in modern IUPAC numbering).
• They are inert.
• They have a full outer electron shell.
• It making them stable and unreactive.

Last verified on 07-11-2026

Explanation

The formula to calculate max electrons in an orbit is 2n², where n = orbit number.

1. 1st orbit (n = 1): 2 × 1² = 2 electrons
2. 2nd orbit (n = 2): 2 × 2² = 8 electrons
3. For the 3rd orbit (n = 3): 2 × 3² = 18 electrons

Last verified on 07-11-2026

Explanation

• Sir James Chadwick discovered the neutron in 1932.
• He was a British physicist.
• His discovery completed the basic picture of the atomic nucleus.
• He received the Nobel Prize in Physics in 1935 for this discovery.

Additional information:

• J. J. Thomson – Electron (1897)
• Ernest Rutherford – Atomic nucleus (1911) and Proton (1917)

Last updated by NA on 05-11-2026

Explanation

• An electric fan uses electrical energy to rotate its blades, producing mechanical motion.
• This mechanical energy helps in circulating air to provide cooling.

Last verified on 07-11-2026

Explanation

• The SI unit of energy is the Joule (J).
• It is the unit of energy, work, and heat.

Additional information:

• 1 Joule (J) = 1 Newton × 1 meter
• Calorie – 1 cal = 4.184 J
• Kilowatt-hour (kWh) – 1 kWh = 3.6 × 10⁶ J
• Electronvolt (eV) – 1 eV ≈ 1.602 × 10⁻¹⁹ J
• Erg (CGS unit) – 1 erg = 10⁻⁷ J

Last verified on 17-01-2026

Explanation

Newton's second law relates force, mass and acceleration.

Acceleration = Force ÷ Mass = 20 ÷ 5 = 4 m/s².

Last verified on 07-11-2026

Explanation

• Inertia is the resistance of an object to a change in its state of motion.
• Greater mass means greater inertia.

Last verified on 07-11-2026

Explanation

• The direction of velocity continuously changes during circular motion.
• Centripetal acceleration acts toward the centre of the circular path.
• Constant speed does not mean constant velocity.

Last verified on 07-11-2026

Explanation

• The product of mass and velocity is known as momentum. P = MV
• If m is an object's mass and v is its velocity (also a vector quantity), then the object's momentum p is: p=mv
• It is a vector quantity.
• It having both magnitude and direction.
• Common symbols: p, p
• SI unit: kg⋅m⋅s−1
• Dimension MLT^−1

Last updated on 09-03-2026

Explanation

• The unit of pressure is N/m² (Newton per square meter).
• It is also called Pascal (Pa).
• Pressure means force applied per unit area.
• Higher force or smaller area increases pressure.

Last verified on 17-06-2026