Explanation

An optical fiber is a flexible,

transparent fiber made by drawing glass  or plastic

To a diameter slightly thicker than that of a human hair.

Explanation

The unit of gas billing is typically the British Thermal Unit (BTU), which measures energy.

It quantifies the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Explanation

Non-flowering plants are called cryptogams.

It include groups like algae, mosses, and ferns, as they reproduce without seeds or flowers.

Explanation

Tiger, (Panthera tigris), the largest member of the cat family (Felidae)

while

The rusty-spotted cat (Prionailurus rubiginosus) is one of the cat family's smallest members

ND5-07-2023

Explanation

Women's voices typically have a high frequency.

This making them sound sharper or higher-pitched compared to lower-frequency male voices.

Explanation

Water vapor is the gaseous form of water.

It present in the atmosphere as an invisible gas.

It is part of the water cycle.

Explanation

Sedimentary rocks are also called stratified rocks.

Explanation

Venus orbits the Sun anti-clockwise but spins clockwise on its axis.

This unique rotation is known as retrograde rotation.

Explanation

Hydrogen is the lightest element, and its most common isotope (protium) has no neutrons in its atomic nucleus.

The atomic number of hydrogen is 1, which means it has one proton in its nucleus, but no neutrons.

The three main isotopes of hydrogen:

• Protium (1H): 1 proton, 0 neutrons
• Deuterium (2H or D): 1 proton, 1 neutron
• Tritium (3H or T): 1 proton, 2 neutrons

Explanation

1. Oxygen: The most abundant element in the Earth's crust, making up about 47% of the Earth's mass.
2. Silicon: The second most abundant element in the Earth's crust, making up about 27.7% of the crust 
3. Aluminum: The third most abundant element in the Earth's crust, making up around 8.1%.