CSS, PCS, ISSB and other Competitive examination preparation

The sun has three main parts: the core, the radiative zone surrounding the core, and the convective zone around that. The core of the sun makes up the inner 25 percent. The radiative zone makes up 45 percent of the sun’s radius, and the convective zone makes up 30 percent of it. The gravity of the sun pulls its mass inward, creating a lot of pressure. This pressure forces atoms of hydrogen to fuse together in nuclear reactions, like nuclear bombs that people build. The energy gives off different kinds of light, like infrared light, ultraviolet light and visible light. Microwaves, radio waves and X-rays also come from the sun. The sun also gives off energized particles that make up solar wind. The energy from solar wind warms the Earth and influences the weather. Thanks to the Earth’s atmosphere, most of the sun’s radiation and solar winds doesn’t harm us HOW SUN WORKS? . source: http://discoverykids.com/articles/how-does-the-sun-provide-heat-and-light/ h...

                     Christians and Muslims have one striking thing in common: they are both “people of the book” And they both have an obligation to spread the Word — to get those Holy Books into the hands and hearts of as many people as they can. (The Jews, the third people of the book, do not feel quite the same obligation.) Spreading the Word is hard. The Bible is almost 800,000 words long and is full of about begetting. The Koran is a mere four-fifths of the length of the New Testament; but some Westerners find it an even more difficult read. Yet over 100m copies of the Bible are sold or given away every year. Annual Bible sales in America are worth between $425m and $650m; Gideon's International gives away a Bible every second. The Bible is available all or in part in 2,426 languages, covering 95% of the world's population. The Koran is not only the most widely read book in the Islamic world but also the most widely ...

What's common to boiling water, artificial rain and the Mentos-Diet Coke reaction? It's nucleation! Let's see what that means. So what is nucleation? How does rain happen in nature? As wind passes over the sea, it collects evaporating water as very, very tiny drops. As the wind rises high in the air, temperatures become very cold, causing some of these drops to merge. This bigger drop attracts more drops of water, and so on and on. This process is called nucleation. When the water drops become about 0.1 mm thick, they cannot float in the air anymore. They then fall to the ground as rain. HOW TO MAKE ARTIFICIAL RAIN IN URDU?     Artificial rain Sometimes it does not get cold enough in the cloud for nucleation to occur. But if we want the cloud to rain, we have to create places where nucleation can occur. This is done by a method called cloud seeding. Tiny particles of silver iodide are sprayed on a cloud from an aeroplane. Sometimes, solid carbon d...