Chemistry -Important Points For Exams

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Chemistry

 

1- Hydrogen gas is released when a metal reacts with an acid .

2- Lime water turns milky when carbon dioxide is passed due to the formation of CaCO3

3-Acids react with metal carbonates to liberate Carbon dioxide gas.

4- You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. Which will turn red litmus to blue. Ans-Base

5-Acids react with bases to form salt and water. This reaction is known as Neutralisation.

6- Acids have pH more than 7.

7- A calcium compound reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. The compound and the gas evolved are Calcium Carbonate, Carbon dioxide.

8-The milkiness (on passing excess carbondioxide gas through lime water) disappears due to the formation of Calcium hydrogen carbonate CaHCO3.

9-cyclohexane is C6H12

10-100% pure ethanol is called Absolute alcohol

11-Wohler prepared urea the first time by heating ammonium cynate.

12-Carboxylic acid containing one carbon atom is Formic acid

13-The difference in the molecular formula and molecular mass of CH4 and C2H6 is CH2 and 14u

14-Ethane and ethene can be distinguished by using Bromine water

15-silicon is a semi – metal.

16-The most metallic element in the fourth period is K.

17-Group 17 elements are also called as halogens

18-The correct order of decreasing metallic character of elements Na, Si, Cl, Mg, Al is Na> Mg> Al> Si> Cl

19-Bauxite is an are of Aluminium metal

20-A list of metals arranged in the order of their decreasing activities is known as Reactivity series.

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