What makes sap go up a tree? One theory ascribes it to osmotic pressure. Liquids and dissolved substances pass through membranes in living things. This is called osmosis. Dissolved chemicals in contact with a membrane press against it. This is osmotic pressure. Yet another holds...
What causes the ‘pop’ in soda pop? Soda pop is a mixture of flavoured syrup, water and other ingredients. Carbon dioxide is also added under pressure. The mixture, still under pressure, is sealed in containers. Part of the carbon dioxide is trapped in the empty...
Which is the deadliest snake? The king cobra is believed by many to be the world’s deadliest snake. It is the longest poisonous snake in the world and its poison is very powerful. It is quick to attack and victims often die in less than...
What is latent heat? Materials cannot absorb heat indefinitely. After a while the heat makes the substance change its state. If the substance becomes cool and turns back into a solid or liquid state, the latent heat is released into the surroundings.
What is a miracle? A miracle is something that cannot be explained using reason and logic. It is a supernatural event. Sometimes things that happen are beyond our understanding and those of us who are religious put it down to divine intervention. Such events are...
How is copper obtained from ore? Copper is found in nature in two forms—native copper or the metal itself or in mineral ore, where it is combined with other elements. Copper ore is refined to get copper. The ore is crushed and washed in flotation...
Do molecules have weight? A molecule’s weight depends on the weight of the atoms it is made of. The weight of the atom depends on the number of protons and neutrons in the nucleus of an atom. For example, hydrogen is a simple atom which...
Why does ice float? The Archimedes principle says that any object when placed in liquid is buoyed up or held up by a force equal to the weight of the displaced liquid. Ice is nine-tenths as heavy as water. So about nine-tenths of an iceberg...
What is slate? Millions of years ago, fine grains of clay particles settled on the bottom of lakes and seas, forming soft mud. This became hardened mud-rock called shale. Around this time, the earth’s crust moved and shifted. The shale layers, covered by beds of...
What is virgin wool? Wool is sometimes used more than once as it is valuable. Old wool is recovered, cleaned and used again. To protect the interests of buyers, some governments made laws which laid down that woollen products should have a label showing the...
