Discovery of virus

-
Discovery of virus

 Virus was discovered by a Russian scientist Ivonowasky in 1892 from Tobacco leaves.

Comments

Post a Comment

Popular posts from this blog

Refraction of light

-
Image
      Refraction of light The change in direction of light when it passes from one medium to another obliquely is called refraction of light.           In other words the bending of light when it goes from one medium to another obliquely is called refraction of light.           The  Refraction of light  takes place when light rays enter from air into glass , or from glass into air. The refraction of light takes place when light enters from air into water, or from water into air. And the refraction of light also takes place when light enters from water into glass or from glass into water.        The optical instruments like camera, microscope and telescope work on the the refraction of light through glass lenses.     The refraction (or bending ) of light takes place at the boundary between the two media. Causes of refraction- The refraction of light  is due to th...
Read more

Blood circulatory system (Blood vascular system )

-
Image
Blood circulatory system    (Blood vascular system ) Blood circulatory system is regarded as a kind of vascular system and therefore, it is called blood vascular system. A vascular system is that which has tubes full of fluid to be transported from one place to another.  The blood vascular system comprises of heart, the organ which pumps and receives the blood, and blood vessels, which are tubes through which the blood flows.      Blood vessels- The blood vessels are elastic muscular tubes which carry blood. There are three kinds of blood vessels in human body.     They are of three types-(1)Arteries  (2)veins and  (3)capillaries. (1)Arteries- Arteries are the thick walled blood vessels which carry blood away from the heart for distribution to the body. The walls of arteries particularly those near the heart are thick that enables them to dilate but not rupture when the heart contracts and forces blood into...
Read more

ईथर के निर्माण की सामान्य विधियाँ ( General methods of preparation of Ethers )

-
ईथर के निर्माण की सामान्य विधियाँ (General methods of preparation of Ethers ) ईथर का निर्माण निम्न विधियों द्वारा किया जा सकता है - (1) हैलोऐल्केन द्वारा -  हैलोएल्केन (एल्किल हैलाइड) से ईथर बनाने के लिए निम्नलिखित विधियां प्रयोग में लाई जाती है- (a) विलियमसन संश्लेषण द्वारा - यह ईथर निर्माण की एक श्रेष्ठ विधि है| इस विधि में एल्किल हैलाइड की क्रिया उपयुक्त सोडियम (या पोटैशियम)अल्कॉक्साइड के साथ कराई जाती है| R-ONa + R-X ------> R-O-R + NaX  CH3-ONa + CH3Br  ------> CH3-O-CH3 + NaBr   C6H5-ONa + CH3Br  ------> C6H5-O-CH3 + NaBr  (b) हैलोएल्केन को शुष्क सिल्वर ऑक्साइड के साथ गर्म करके-  हैलोएल्केन को शुष्क सिल्वर ऑक्साइड के साथ गर्म करके भी इधर का निर्माण किया जा सकता है जैसे- 2CH3CH2Br + Ag2O -------> CH3-O-CH3 + 2AgBr  (2) ऐल्कोहलो से - (a) ऐल्कोहलो के निर्जलन से - जब अल्कोहल के आधिक्य को 413 K पर सांद्र H2SO4 के साथ गर्म करते हैं तो एक अणु ईथर व एक अणु जल बनता है |                   ...
Read more