Test: Acids Bases & Salts - Class 7 MCQ

When phenolphthalein is added to a basic solution, it changes its color to dark pink. This change helps us know if a solution is basic or not. So, when you see the pink color, you can tell that the solution is basic.

Litmus paper is used as an indicator to check acids and bases. Acids turn blue litmus red.
Litmus is a mauve (purple) colour pigment obtained from Lichens. It turns red when added to acidic solution and blue when added to a basic solution.

• True! Acids like curd, lemon juice, orange juice, and vinegar taste sour because they contain acids.
• On the other hand, bases like baking soda taste bitter.
• So, acids usually have a sour taste, while bases have a bitter taste.
• When you taste something sour like lemon juice, it might have acids in it.
• And if something tastes bitter like baking soda, it could be a base.
• Remember, sour for acids and bitter for bases!

In the neutralization reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH), the new substance formed is sodium chloride (NaCl), commonly known as table salt. This salt is produced along with water (H2O) as the products of the reaction, highlighting the typical outcome of a neutralization process between an acid and a base.

Turmeric is a natural acid-base indicator. It turns yellow in an acidic medium and changes its colour to red in a basic medium.

Litmus paper turns red when added to an acidic solution. This color change is a result of the acidic nature of the solution, which causes the litmus paper to shift its color to red. It is a simple and effective way to test for acidity using a natural indicator like litmus.

Acetic acid is the acid commonly found in vinegar. It is a weak acid that gives vinegar its characteristic sour taste and pungent smell. Acetic acid is also widely used in the food industry for pickling and preserving food items.