Acids, Bases and Salts — Class 10 Science PYQs

Which one of the following can be used as an acid-base indicator by a visually impaired (blind) student ?

The natural sources of oxalic acid, lactic acid and methanoic acid respectively are :

(a) Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode.
OR
(b) Write the preparation of following compounds with balanced chemical equation :
(i) Baking soda
(ii) Bleaching powder
(iii) Plaster of Paris

The following table shows the pH values of four solutions A, B, C and D on a pH scale :
1 2 3 4 5 6 7 8 9 10 11 12 13 14
The solutions A, B, C and D respectively are of a

Consider the following reactions :
(i) Dilute hydrochloric acid reacts with sodium hydroxide.
(ii) Magnesium oxide reacts with dilute hydrochloric acid.
(iii) Carbon dioxide reacts with sodium hydroxide.
It is found that in each case :

In one formula unit of salt 'X', seven molecules of water of crystallisation are present. The salt 'X' is :

Tooth enamel is made up of calcium hydroxyapatite (a crystalline form of calcium phosphate). This chemical starts corroding in the mouth when the pH is :

Seawater contains many salts dissolved in it. Common salt is separated from these salts. Deposits of solid salt are also found in several parts of the world. These large crystals are often brown due to impurities. This is called rock salt and is mined like coal. The common salt is an important raw material for chemicals of daily use.
(a) Write balanced chemical equations to show the products formed during electrolysis of brine.
(b) List two uses of any one product obtained during electrolysis of brine.
(c) (i) A mild non-corrosive basic salt 'A', used for faster cooking, is strongly heated to produce a compound 'B', that is used for removing permanent hardness of water. Identify A and B and also write the equation for the reaction that occurs when A is heated.
OR
(c) (ii) Define water of crystallisation. Give two examples of salts that have water of crystallisation.

The warning sign shown in the given figure must invariably be displayed/pasted on the containers which contain hydroxide of :

The body of human beings works within the pH range of :