Chemical change is the burning of wood and cutting of wood is a physical change. The burning of wood produces ash and smoke that means two new substances are formed. Wood (cellulose ) changes into ash , carbon dioxide and water . Hence the properties of wood are changed. So, it’s a chemical change. When …
When some sour substance or curd ( lactobacillus bacteria ) is added to milk and kept long time, it turns into curd. Once the curd is formed, then there is no way curd can be converted back into milk. Both milk and curd are different and they have different properties So, the formation of curd …
How would you say that setting of curd is chemical change ? Read More »
The wax of the candle melts, then vaporizes and burns. Here Melting of wax is a physical change as no new substance is formed and the melted wax can be converted back to solid wax. When the wax burns, two new substances are formed which are water and carbon dioxide. So, it’s a chemical change. …
Rusting is the process in which iron in the open air acquires a iayer of a brownish substance called rust. For rusting, iron should be in contact with both air and moisture. When an iron gate is painted then the layer of paint cuts off the contact between air, moisture from iron. Thus, it prevents …
Explain how the painting of an iron gate prevents it from rusting. Read More »
he difference between the acids and bases are: Acids Base Acids are sour in taste Bases are bitter in taste Acids turn blue litmus to red, bases do not change the colour of blue litmus. Acids do not change the colour of red litmus. Bases change the colour of red litmus to blue.
An acid and a base neutralise each other and form a salt. A salt may be acidic, basic or neutral in nature.
Our stomach contains hydrochloric acid. It helps us to digest food, . But too much of acid in the stomach causes indigestion. Sometimes indigestion is painful. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralises the effect of excessive acid.
The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms.The factory wastes are, therefore, neutralised by adding basic substances.
Excessive use of chemical fertilisers makes the soil acidic. Plants do not grow well when the soil is either too acidic or too basic. When the soil is too acidic, it is treated with bases like quick lime (calcium oxide) or slaked lime (calcium hydroxide). If the soil is basic, organic matter (compost) is added …
When an ant bites, it injects the acidic liquid (formic acid) into the skin. The effect of the acid can be neutralised by rubbing moist baking soda (sodium hydrogencarbonate) or calamine solution, which contains zinc carbonate.
