221 Facts Tell Me What

Fire is an occurrence related to burning. When a thing burns at a fast speed, it produces heat along with flames. These flames are called ‘fire’. The size of fire depends on the amount of combustible material and presence of oxygen. Oxygen is necessary for burning. Atmospheric lighting was the original source of fire on […]

Fossils tell us what types of organisms lived millions of years ago. They give us an idea of early man, too. The study of fossils is known as ‘palaeontology’. There are three types of fossils: • It could be an organism’s actual preserved body, appearing like it originally looked.• It could be only the outer

A fog is a kind of cloud, which is found close to the ground or sea surface instead of sky. It is formed when cold air comes in contact with the warm surface of water or land. It is mostly formed at night or in the early morning over small water bodies or lowlands. During

Smoke is the visible gas that comes out after incomplete burning of fuels. If a fuel is completely burnt, it gives off carbon dioxide, water vapour and free nitrogen, and does not give off any smoke. Smoke is generated only when fuels do not get proper conditions for combustion like enough oxygen and high temperature.

The ocean water is salty due to elements, ions and compounds dissolved in it. The constant erosion and breaking down of rocks causes elements, ions and compounds to be continuously washed away to the ocean, through streams and rivers. Though salt keeps coming into the ocean in this manner, it gets removed too through sprays

The presence of water vapour in the air is called humidity. Too much or too little humidity can be dangerous. Humidity is found in all places, but it varies. For example, when a can of ice-cold water is put on the table and allowed to stand for some time, moisture appears on the outside. Moisture

Nails grow from the skin and are composed of a substance called ‘keratin’. Keratin is a tough-dead protein, horn-like in nature. Nails are closely attached to the skin. The exposed part of the nail is very thick, but as we go below the skin, near the root of the nail, we find that it is

We cannot imagine a world without light. Light lets us see. Light was first studied by Sir Isaac Newton. He said that light consisted of minute particles which are shot out from the source of light. Another theory was suggested by Huygens. He said that light is in a form of ‘wave’ or ‘pulse’. Light

Sneezing is a reflex action that happens without our control. We may sneeze due to irritation in the nose, due to a swelling in the mucous membrane, during a cold or an allergy. People sneeze to expel air and rid themselves of the irritating bodies present in the nose. When the inside of the nose

The phenomenon of colour was first discovered by Sir Isaac Newton. He proved that sunlight comprised several colours. He passed a beam of sunlight through a prism and discovered that the white light ray is a mixture of many colours. Without light, there is no colour. So, colour isn’t in the objects that we see

Optical illusion is a trick played by our eyes on us. When we see an object, the actual image detection is done by our brain. The cells in the brain are the real decision makers about what the eyes are seeing. In case of an optical illusion, the brain sees things which may or may

Thoughts are impulses that originate from our brain. The speed of these impulses cannot be measured accurately; however, it has been calculated that thoughts travel at a speed of 241 km per hour. This speed is lower than the speed of messages conveyed through television, email, etc. The speed of thought varies according to the

Daydreaming is dreaming with open eyes. Almost everybody daydreams. Daydreams are usually an expression of desires, ambitions, wants or needs. The dream gives us the chance to accomplish, in our thoughts, something that we want to do or want to get. In other words, daydreaming is an outlet for our innermost feelings and thoughts. At

Birthmarks are coloured marks on the skin that are noticeable at birth, or shortly afterwards. There are two types of birthmarks: pigmented and vascular. Pigmented birthmarks are caused by clusters of pigment cells; they are usually tan or brown-coloured. Vascular birthmarks are caused by abnormal blood vessels in or under the skin; they are often

A person goes through various stages of physical and mental growth. All children have different physical stature and strength. They also have different levels of mental development. To measure an individual’s mental level of development, a series of tests have been made. These tests are called IQ (relative intelligence of a person) tests. ‘IQ’ is