Explanation

• Only about 2.5% (3%) of the water on Earth is freshwater, which is vital for human consumption, agriculture, and ecosystem health.
• The remaining 97.5% (97%) is saltwater, found in oceans, seas, and salt lakes.

Explanation

The main constituent of hemoglobin is iron.

Hemoglobin transports oxygen and exhibits a quaternary protein structure.

Iron is crucial for hemoglobin formation; its deficiency can impact hemoglobin production.

Heme in hemoglobin is protoporphyrin IX.

Infants reach adult hemoglobin levels by the end of their first year.

Ferric ions are not part of hemoglobin.

Hemoglobin is found dissolved in plasma.

Explanation

Aluminum is the most abundant metal in the Earth's crust.

It comprising about 8% of its weight.

It is primarily found in the form of bauxite ore.

Explanation

Thomas Savery is considered the inventor of the first commercially used steam-powered device.

In 1698, he patented a steam-powered pump designed to remove water from mines.

Explanation

• The speed of sound in air at 0°C (32°F) is 332 meters per second.

The speed of sound in different materials:

• Air: 332 m/s
• Sea water: 1530 m/s
• Lead: 2160 m/s
• Gold: 3240 m/s
• Brick: 3650 m/s
• Copper: 4760 m/s
• Glass: 5100 m/s
• Aluminium: 6420 m/s

Explanation

The standard meter and kilogram are made from an alloy of platinum and iridium to ensure durability and accuracy.

This alloy is used because it resists corrosion and retains its shape over time, crucial for precise measurement.

Explanation

The prefix "Tera" refers to 10^12.

It is commonly used to represent a trillion in the metric system (1,000,000,000,000).

Explanation

• When red litmus paper is dipped in a basic solution, it turns blue.
• This indicates that the solution is basic, or alkaline.

Note: When blue litmus paper is dipped in an acid solution, it turns red.

Explanation

 The additional, small, circular, extrachromosomal piece of DNA in a bacterial cell is called a plasmid.

Structure: Small, double-stranded, circular DNA molecules.

Location: Found in the cytoplasm of bacteria (extrachromosomal).

Function: They typically contain non-essential but advantageous genes, such as those for antibiotic resistance.

Last updated 17-02-2026

Explanation

Washing soda, also known as sodium carbonate (Na₂CO₃).

It is made up of sodium (Na), carbon (C), and oxygen (O).

It is commonly used for cleaning purposes due to its ability to soften water and remove stains.