Compounds such as alcohols and glucose also contain hydrogen but are not categorised as acids. Describe an Activity to prove it.
Because glucose and alcohol do not dissociate into ions. Therefore these solution are not considered as acid -
Experimental verification :
Procedure : Two nails are fitted in a cork and they are kept in a 100 ml beaker. Then the nails are connected to the two terminals of the battery of 6 volt along with a bulb and a switch. Now some dilute HCl is added in the beaker and allows the current to pass through the circuit. The same experiment is carried out with glucose and alcohol solutions separately in place of HCl.
Observations :
The bulb glows only in HCl solution only. Because HCl solution dissociates into H+ and Cl– ions which conduct electricity whereas glucose and alcohol solutions do not dissociate into ions and so, these solutions do not conduct electricity. So the bulb doesn't glow.
Interpretation :
Activity above hereby proved that all acids contain hydrogen but not all compounds that contain hydrogen are acids. Therefore compounds such as alcohols and glucose contain hydrogen, and are not categorised as acids.
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.
Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.
What are amphoteric oxides? Give two examples of amphoteric oxides.
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Explain the terms analogous and homologous organs with examples.
What are the limitations of extracting energy from—
(a) the wind? (b) waves? (c) tides?
What are the limitations of the energy that can be obtained from the oceans?
What are the qualities of an ideal source of energy?
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
If you could use any source of energy for heating your food, which one would you use and why?
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?