Class 7 Science Chapter 4 MCQ

Lemon water is acidic in nature. Acids do not turn all indicators red e.g. china rose indicator turns to dark pink (magenta) when acidic compound is added to it. Common salt and water both are neutral. Hence, have no effect on litmus.

Turmeric paste is yellow in acidic solution and turns red in basic solution.

Here, all the statements are correct. Hence, your answer should be option [D].

Phenolphthalein remains colour-less in acidic solution but turns pink in basic solution.

Red litmus gives red colour in lemon juice which cannot be seen because red color mix with red litmus paper. Rest of all options are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Organic matter (called manure or compost) releases acids which neutralize the excess bases present in the soil and reduce its basic nature.

Here all the statements, which are related to indigestion, are correct. Hence, your answer will be option [D].

Here all the statements are correct. Hence, your answer will be option [D].

Here all the statements are correct. Hence, your answer will be option [D].

Neutralization reaction is a chemical reaction between acid and base to produce salt and water. It cannot be reversed.

Basic solution changes the turmeric indicator from yellow to red.

When litmus is added to a basic solution it turns “blue”. Rest of all statements are correct. Hence, your answer will be option [D].

Bases turn china rose indicator to “green”. Rest of all statements are correct. Hence, your answer will be option [C].

Here all the statements are correct. Hence, your answer will be option [D].

Curd contains lactic acid and vinegar contains acetic acid. Lime water, soap and milk of magnesia are basic substances and grapes contain tartaric acid.

Phenolphthalein indicator is synthetic (man-made), acid-base indicator. Rest of all statements are correct. Hence, your answer will be option [A].

Phenolphthalein is colourless in acidic and neutral medium but turns pink when introduced in basic medium.

Hydrochloric acid, sulphuric acid and nitric acid are strong acids. On the other hand, acetic acid, formic acid, citric acid, tartaric acid and carbonic acid are some examples of the “weak acid”. Rest of all statements are correct. Hence, your answer will be option [D].

Ammonium hydroxide or ammonia solution is found in window cleaners. Rest of all statements are correct. Hence, your answer will be option [D].

Turmeric paste changes its colour from yellow to red when treated with a base. So, turmeric is an acid base indicator.

Calcium Hydroxide, ammonium hydroxide and sodium carbonate are weak base but their solution are unsafe to drink. Magnesium hydroxide is a very weak base which is safe to drink. It is used in milk of magnesia and other indigestion mixtures.

Red litmus gives red colour in lemon juice which cannot be seen because red color mix with red litmus paper. Rest of all options are correct. Hence, your answer will be option [D].

Acid and base participate in neutralization reaction and produce salt and water.

Antacids are a group of mild bases which have “no” toxic effects on the body. Rest of all statements are correct. Hence, your answer will be option [B].