<h2>Two pieces of information </h2>
Sonar is an instrument which is used to search for things which are underwater. It is also used to find the depth of water by giving out ultrasonic vibrations into the water. The time which the vibrations take to return assists to find the distance of the reflecting surface.
At the same time, carbon dioxide molecules diffuse rapidly out of the red blood cells<span>, down their concentration gradient, and into your lungs. When </span>water<span> molecules </span>move <span>freely </span>across a cell membrane<span>, the process is called OSMOSIS , which is just a special type of simple diffusion.</span>
A true
<span> Before agriculture was developed people mostly were nomadic in nature. They moved from place to place in search of food. Some of them were groups of hunter gatherers as well. When agriculture started people also started to settle down in groups. This led to the development of civilization and in modern day cities and towns. The first agricultural practices were started beside the river banks due to the reason that the soil was very fertile and water for irrigation was also easily available. </span>
