Explanation

• The molecular structure (double-helix model) of DNA was proposed in 1953.
• This model explained how DNA replicates and carries genetic information in living organisms.
• The discovery was made by James Watson and Francis Crick, two molecular biologists.

Last verified on 11-03-2026

Explanation

• Gene Definition: Basic physical and functional unit of heredity
• Location: Found on chromosomes within DNA
• Function: Codes for proteins or RNA molecules that determine traits
• Types: Structural genes (proteins), regulatory genes (control expression)
• Inheritance: Passed from parents to offspring during reproduction

Last verified on 05-02-2026

Explanation

• A chemical reaction that releases heat energy to the surroundings is called an Exothermic Reaction.
• In such reactions, energy is produced in the form of heat, light, or flames.
• Examples include combustion of fuel, respiration, and neutralization reactions.

Additional information:

• An endothermic reaction, which absorbs heat from the surroundings.

Last verified on 11-03-2026

Explanation

• The branch of chemistry that studies heat energy released or absorbed during chemical reactions is called Thermochemistry.
• It explains how heat changes occur during reactions such as combustion, neutralization, and dissolution.
• It deals with concepts like enthalpy change (ΔH), exothermic reactions, and endothermic reactions.

Last verified on 11-03-2026

Explanation

• The formation of hydrogen and oxygen from water, which is an example of a decomposition reaction: 2H2O → 2H2 + O2
• In this reaction, water (H2O) decomposes into hydrogen (H2) and oxygen (O2).

Last verified on 11-03-2026

Explanation

• A Telescope is an optical instrument used to observe distant objects such as stars, planets, and galaxies.
• It collects and magnifies light or other forms of electromagnetic radiation.
• The term “telescope” was coined in 1611 by the Greek mathematician Giovanni Demisiani.

Last verified on 10-03-2026

Explanation

• When water cools from 4°C to 0°C, it expands as it freezes into ice.
• Unlike most substances, water’s maximum density is at 4°C; below this temperature, the volume increases and density decreases.
• This is why ice floats on water.

Last verified on 10-03-2026

Explanation

• Combustion is a chemical reaction in which a substance reacts rapidly with oxygen to produce heat and light.
• Commonly observed when wood, coal, or fuel burns.
• Combustion is an exothermic reaction because it releases energy.

Last verified on 10-03-2026

Explanation

• The atmospheric pressure at any place is measured by a Barometer.
• The barometer was invented by Evangelista in 1644.

Last verified on 10-03-2026

Explanation

• Antoine Lavoisier, a French chemist, is credited with discovering the law of conservation of mass in 1789 (1785).
• He demonstrated that matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.

Last verified on 10-03-2026