Class 10 Science - Chapter Acids, Bases and Salts NCERT Solutions | 10 mL of a solution of NaOH is found to

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

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

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.

What is ozone and how does it affect any ecosystem?

How does the creation of variations in a species promote survival?

The human eye forms the image of an object at its

(a) cornea.          (b) iris.          (c) pupil.          (d) retina.

Name two safety measures commonly used in electric circuits and appliances.

On what factors does the resistance of a conductor depend?

What change will you observe if you test soap with litmus paper (red and blue)?

Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

Find the focal length of a lens of power – 2.0 D. What type of lens is this?

Write equations for the reactions of

   (i) iron with steam
   (ii) calcium and potassium with water.

How can you help in reducing the problem of waste disposal? Give any two methods.