Class 10 Science - Chapter Acids, Bases and Salts NCERT Solutions | Metal compound A reacts with dilute hydr

Why does distilled water not conduct electricity, whereas rain water does?

Plaster of Paris should be stored in a moisture-proof container. Explain why?

A solution turns red litmus blue, its pH is likely to be

  (a) 1          (b) 4          (c) 5          (d) 10

Give two important uses of washing soda and baking soda.

Why should curd and sour substances not be kept in brass and copper vessels?

Why do HCl, HNO₃, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?

Five solutions A,B,C,D and E when tested with universal indicator showed pH as 4,1,11,7 and 9, respectively. Which solution is

(a) neutral?
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?

Arrange the pH in increasing order of hydrogen-ion concentration.

Name the substance which on treatment with chlorine yields bleaching powder.

A milkman adds a very small amount of baking soda to fresh milk.

   (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
   (b) Why does this milk take a long time to set as curd?

Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.

What is a good source of energy?

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What changes can you make in your habits to become more environment-friendly?

What is the difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Why should a magnesium ribbon be cleared before burning in air?

Define the principal focus of a concave mirror.

The autotrophic mode of nutrition requires

         (a) carbon dioxide and water.         (c) sunlight.
         (b) chlorophyll.                                (d) all of the above.

Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements:

    K,     C,      AI,      Si,      Ba.

Which of the following lenses would you prefer to use while reading small letters found in a dictionary?

(a) A convex lens of focal length 50 cm.
(b) A concave lens of focal length 50 cm.
(c) A convex lens of focal length 5 cm.
(d) A concave lens of focal length 5 cm.

Why is vegetative propagation practised for growing some types of plants?

Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Explain why the planets do not twinkle.

Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?

Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

How is the process of pollination different from fertilisation?