Explanation

• At the center of the Earth, g = 0.
• Gravity from all directions cancels out at the center.
• So net gravitational force becomes zero.
• An object would feel weightless there.
• This is due to symmetrical distribution of Earth's mass.
• Earth’s surface gravity: 9.8 m/s²

Last verified on 17-06-2026

Explanation

• All electromagnetic waves travel through a vacuum at 3x10^8 m/s.
• This is the speed of light (c).
• Radio waves, microwaves, visible light, X-rays and gamma rays all have the same speed in vacuum.

Last verified on 31-10-2026

Explanation

• Earth's magnetic field varies in both strength (magnitude) and direction from place to place.
• Its direction changes with geographic location and is not the same at the magnetic equator and poles.
• Its strength is generally weaker near the magnetic equator and stronger near the magnetic poles.

Last verified on 31-10-2026

Explanation

Molar mass CO = 12 + 16 = 28 g/mol

Molar mass N₂ = 14×2 = 28 g/mol

14 g CO = 14/28 = 0.5 moles of CO - Correct

14 g N₂ = 14/28 = 0.5 moles of N₂ - So Same moles of CO and N₂ - Correct

Volume at STP = 0.5 × 22.4 = 11.2 dm³ - Correct

Molecules = 0.5 × 6.02×10²³ = 3.01 × 10²³

So 1.5 × 10²³ is half the actual value, therefore it is the incorrect statement.

Last verified on 30-10-2026

Explanation

In absence of air resistance, the only force is gravity.

So vertical acceleration is g. g is constant during whole flight.

It is same at P, at T, and at Q. 

So answer is The same at Q as at T.

Last verified on 30-10-2026

Explanation

• Angular velocity is the rate of change of angular displacement with time.
• Its dimensional formula is [T⁻¹].
• Frequency is also measured in hertz (Hz), equivalent to s⁻¹, so both have the same dimensions.

Last verified on 30-10-2026

Explanation

• Mass defect is the difference between the total mass of separate nucleons and the actual mass of the nucleus.
• It occurs because some mass is converted into binding energy when the nucleus is formed.
• Einstein's mass-energy relation is E=Δmc².

Last verified on 30-10-2026

Explanation

W = PΔV = 25 x 10³ x (48 - 20) x 10⁻³

W = 25 x 10³ x 28 x 10⁻³ = 700 J

First law: Q = ΔU + W

1200 = ΔU + 700

ΔU = +500 J

Last verified on 30-10-2026

Explanation

• Potential difference is the work done per unit electric charge.
• Its SI unit is the volt (V).
• One volt is equal to one joule per coulomb (1 V = 1 J/C).

Last verified on 30-10-2026

Explanation

Electric flux density = Total flux / Area

= 12,000 / 6 cm² 

= 2000 lines per cm² 

= 2.0 x 10⁷ lines per m² = 20 x 10⁴ lines per cm² in CGS units.

Last verified on 30-10-2026