Which of the following sets of substances are basic in nature?

The salt solution which does not react with ammonium hydroxide is:

 Circle the odd ones. Give reasons for your choice:

Spinach    curd        tomato        guava

Which of the following are acidic and which are basic?

Lime water, Vinegar, Toothpaste, Stomach juice, Lemon juice, Baking soda solution, Milk of magnesia, Ammonia solution.

Mark circle for odd man out:

sulphuric acid    nitric acid    lactic acid    hydrochloric acid