fourth grade free math in children's science & nature books

> Atomatic number of the elements 1st Period n = 1 Short period 2 Atomic number 1 and 2 2nd Period n = 2 Short period 8 Atomic number 3 to 10 3rd Period n = 3 Long period 8 Atomic number 11 to 18 4th Period n = 4 Long period 18 Atomic number 19 to 36 5th Peri..

Thymus - It is a gland that is prominent behind the breastbone in children. It gradually decreases in size in adults. It secretes hormone called thymosin. Thymosin helps in the production of lymphocyte..

This is the most communicable disease in our country and effects mainly children in the age group 0-15 years. Every year 2.5 million people suffer from typhoid. Caused by bacterium salmonella typhi, it passes out through the excreta of the infected person. This is spread by houseflies or ..

It is secreted by the secretory glands of the stomach wall. It is highly acidic as it contains hydrochloric acid (HCl). It also contains enzymes like pepsin and renin. Both act on proteins. However, renin is present only in young children. It digests the milk proteins. Pepsin is secreted..

Increasing population is a serious issue, particularly in developing countries. It is necessary for every generation to produce more off springs because many individuals do not survive to reach the reproductive age due to natural causes. However, man has upset this equation as he has been successf..

Children between 1-3 years of age must consume 1g protein/kg body weight. If they consume below this quantity they can suffer from this protein deficiency diseas..

Gastric Juice - It is secreted by the secretory glands of the stomach wall. It is highly acidic as it contains hydrochloric acid (HCl). It also contains enzymes like pepsin and renin. Both act on proteins. However, renin is present only in young children. It digests the milk proteins. Pep..

. The food then moves into the stomach. The opening is controlled by the cardiac sphincter which is a muscular ring. The stomach opens only in response to swallowing. Here the proteins are broken down into proteoses and peptones by the action of pepsin and the soluble milk protein caesinogen is deg..

. In 1793, he left for Manchester to teach physics and chemistry in a college. In 1801, he observed and discovered the law of expansion of gases on heating. He also enunciated the law of partial pressures and found methods of determining vapour pressure of gases. He invented the dew point hygromete..

Very few metals exist in the free or native state. Only metals like gold, platinum and mercury are occasionally found in the free state i.e., in the pure form. Sometimes, copper and silver may also be found in the free state. Such metals are not acted upon by air or w..