Were dinosaurs’ eggs also big? Dinosaurs laid 10 to 40 eggs at a time. The size of the eggs depended on the size of the adult dinosaur. But they were not very large. A 30-m long female dinosaur might lay an egg that was 60...
How do migrating salmon return to the place where they were hatched? Salmon migrate from freshwater streams and rivers to the sea. They return to their birthplace to reproduce. It is believed that the position of the sun and the stars as well as the...
What is a Plimsoll line? On the side of a ship one can see a line or a series of lines. This is called a Plimsoll line. These lines mark the highest safe water level in various conditions. This is to make sure that ships...
Were the Mayans skilled in astronomy? The Mayans knew astronomy very well. They studied the sun, moon, stars and planets. They were also good at maths. They had a calendar for counting days and years. They also knew how to predict events like eclipses.
Why do some birds have colourful feathers? Birds have colourful feathers to attract mates. The male peacock is a good example. At the same time peahens are dull in colour. Bright feathers also serve to warn other males to keep off. Unlike the case of...
What is the size of a molecule? A molecule is the smallest part of a substance which can exist without giving up the properties of the whole. Some molecules are simple, others are complicated, with thousands of atoms arranged in an intricate manner. Gases like...
What is aluminium? Aluminium is a metal which forms almost 8% of the earth’s crust. It is the most abundant of all the metals. It is not found free in nature. It is found combined with other substances forming parts of rocks and soils. Sapphires,...
Who was Julius Caesar? Julius Caesar was a great Roman general. He made himself the dictator of Rome for life. He was able to bring peace and also passed many good laws. But the senate thought he had too much power and decided to assassinate...
Why do dogs pant? Dogs pant to cool off. When the heat unbearable, they stick out their tongues and pant. Dogs do not perspire like human beings. When a dog pants, its breath blows away moisture from its mouth, nose and lungs. This has a...
What causes typhoid fever? Typhoid fever is caused by a bacillus named salmonella typhosa. It is found in excreted products. Symptoms of the disease include fever, headaches, chills and sweats. One attack can grant lifelong immunity to a person. It can be prevented by keeping...
