WHAT MAKES PEOPLE SNEEZE ???

According to Biology, Sneezing is an involuntary reflex action.It occurs when the nerve endings of the mucous membrane of the nose get irritated. This irritation can occur due to the swelling of the mucous membrane. This happens when we get cold. This also occurs due to the foreign bodies that somehow manage to enter into the nose. Again, even allergies produce irritation. The act of sneezing is an attempt by the body to expel air to get rid of irritating bodies. Sometimes, sneezing also occurs when the optic nerve is stimulated by a bright light. During the act of sneezing, our whole body gets a jerk because the air comes out with the great speed- about 160 km per hour. The whole body vibrates and the eyes automatically gets closed. In fact, we cannot keep our eyes open during sneezing even if we try to do so.

https://www.google.co.in/search?q=images+of+sneezing&hl

(source : Children's Knowledge Bank, volume II, Topic: Human Body, page :92, 2nd para)

Amazing Facts...

1. There are 62,000 miles of blood vessels in the human body – laid end to end they would circle the earth 2.5 times
2. At over 2000 kilometers long, The Great Barrier Reef is the largest living structure on Earth.
3. A typical hurricane produces the energy equivalent of 8,000 one megaton bombs.
4. Blood sucking hookworms inhabit 700 million people worldwide.
5. 65% of those with autism are left handed.
(Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. The diagnostic criteria require that symptoms become apparent before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood.
http://en.wikipedia.org/wiki/Autism)
6. The temperature on the surface of Mercury exceeds 430 degrees C during the day, and, at night, plummets to minus 180 degrees centigrade
7. Butterflies taste with their hind feet, and their taste sensation works on touch – this allows them to determine whether a leaf is edible.


source : http://listverse.com/2007/12/19/top-20-amazing-science-facts/

Chemistry question for class IX

QUESTION:
The %age of three elements calcium, carbon and oxygen in a sample of calcium carbonate is given as-
calcium-40%, carbon-12%, oxygen-48%.
If the law of constant proportion is true, what weights of each elements will be present in 1.5 g of another sample of calcium carbonate?

ANSWER:
Given the atomic mass of ca- 40u. c-12u, o-16u.
Mass=(1) calcium-1.5 x 40/100 = 0.6
           (2)carbon-1.5 x 12/100= 0.18
           (3)oxygen-1.5 x 48/100= 0.72

Moleculer Weight=(1)calcium-40 x 0.6= 24
                              (2)carbon-12 x 0.8= 2.16
                              (3)oxygen-16 x 0.72= 11.52