Explanation

Sound wave is a mechanical  wave.

Electromagnetic waves are waves that consist of oscillating electric and magnetic fields

That propagate through space without needing a medium.

Sound waves, on the other hand, are mechanical waves that require a medium (like air, water, or solids) to travel through. 

Explanation

Explanation

Kirchhoff’s Voltage Law (KVL) states that the algebraic sum of voltages around a closed loop is zero.

This is based on the principle of conservation of energy, as energy is neither created nor destroyed in the loop.

Explanation

A neutron has mass ≈ 1.675 × 10⁻²⁷ kg, very close to a proton’s mass.

An electron is much lighter (≈ 1/1836 of a proton), so not comparable.

Explanation

Velocity SI units: meters per second (m/s or m·s⁻¹).

This unit is derived from the SI units for displacement (meter) and time (second),

Velocity is defined as the rate of change of displacement over time (displacement/time). 

Explanation

The power of the lens is the reciprocal of focal length.

The SI unit is dioptre.

Dioptre (D)

Power of lens = 1/ focal length in meter.

Explanation

An Angstrom (Å) measures very small distances, especially wavelengths of light and atomic-scale lengths.

It is equal to 10^-10 meters, or 0.1 nanometers. 

Therefore, among the given options, angstrom is used to measure the length of light waves.

It is also used to measure other microscopic dimensions, such as: 

• The size of atoms and molecules
• The lengths of chemical bonds
• The arrangement of atoms in crystals

Explanation

Explanation

The atomic weight of Mercury (Hg) is 200.59 unified atomic mass units (u), as listed on the periodic table.

Key Information:

• Symbol: Hg (from Latin Hydrargyrum)
• Atomic Number: 80
• Standard Atomic Weight: 200.592 u (often rounded to 200.59 u).

Explanation

Sodium hydroxide is commonly known as caustic soda.

It is a strong base used in soap making and other chemical industries.