Q34 of 56 Page 1

When you add sodium hydrogen carbonate to acetic acid in a test tube, a gas liberates immediately with a brisk effervescence. Name this gas. Describe the method of this gas.

When acetic acid is added to NaHCO3 solution, and when a burning splinter is brought carbon dioxide gas with brisk effervescence from the test tube.



This gas can be verified by following method:


When carbon dioxide gas is turned through lime water, the lime water turns milky. It turns milky due to formation of Calcium carbonate CaCO3 . The chemical reaction is as follows:



When carbon dioxide is passed through the calcium carbonate, calcium hydrocarbonate is formed and the milkiness of water disappears.



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A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical centre of the lens is 12 cm and its sharp image is formed at a distance of 24 cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way (towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?