Acids, Bases and Salts: Class 10 Science Q&A · Page 4
77 free answers on Acids, Bases and Salts (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10CBSE
Name the sodium compound which is used for softening hard water.
Sodium carbonate is the compound which is used for softening hard water.
- ScienceClass 10CBSE
Name the substance, which on treatment with chlorine, yields bleaching powder.
Solution: The substance, which on treatment with chlorine, yields bleaching powder is Calcium hydroxide.
- ScienceClass 10CBSE
1. What is the common name of the compound CaOCl2?
Solution: The common name of CaOCl2 is bleaching powder.
- ScienceClass 10CBSE
Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide), or chalk (calcium carbonate)?
If the soil is acidic in nature (PH below 7), then such fields should be treated with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate).
- ScienceClass 10CBSE
Do basic solutions also have H+(aq) ions? If yes, then why are these basic?
Solution: Basic solutions have H+ ions, but hydroxide ions present in basic solution are more in basic solution. Hence, Hydroxide ions turn the solution into basic.
- ScienceClass 10CBSE
What effect does the concentration of H+(aq) ions have on the nature of the solution?
Solution: Hydrogen ion concentration decides the nature of the solution. If Hydrogen ion concentration increase, then the solution turns acidic and similarly, if Hydrogen ion concentration decreases, then the solution turns basic.
- ScienceClass 10CBSE
You have two solutions, A and B. The pH of solution A is 6, and the pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of these is acidic, and which one is basic?
In order to find the hydrogen ion concentration, we can use the rule that states, “The pH of any solution is inversely proportional to the hydrogen ion concentration.” Therefore, it means that the solution that has a lower pH number will have a higher hydrogen ion concentration. Hence, solution A will have a higher hydrogen ion concentration. In addition, solution B will be basic, and A will be acidic.
- ScienceClass 10CBSE
How is the concentration of hydroxide ions (OH–) affected when excess base is dissolved in a solution of sodium hydroxide?
When a base is dissolved in sodium hydroxide solution, its hydroxide ions increase, but it will reach saturation at some point. After saturation point, hydroxide ion concentration is not affected even after adding base further.
- ScienceClass 10CBSE
How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
When acid is added to water, there will be a fixed amount of hydronium present in the fixed volume of the solution. If we dilute the solution, hydronium ions per volume of the solution decrease, and this, in turn, decreases Hydronium concentration in the solution.
- ScienceClass 10CBSE
While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
While diluting an acid, it is recommended that the acid should be added to water and not water to the acid because if water is added to a concentrated acid, it releases a huge amount of heat which may result in an explosion and can cause acid burns on the face, clothes and body parts. Hence, it is safe to add acid to water but not water to acid.
- ScienceClass 10CBSE
Why does dry HCl gas not change the colour of the dry litmus paper?
HCl does not give out Hydrogen ions; therefore, HCl does not show any acidic behaviour, and the colour of the litmus paper remains the same on reacting with HCl gas.
- ScienceClass 10CBSE
Why does an aqueous solution of acid conduct electricity?
Charged particles are responsible for the conductance of electricity in an acid. These charged particles, called ions, are the reason behind the conductance of electricity in acid.
- ScienceClass 10CBSE
Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show an acidic character?
Solution: Release of H+ ion in water will make a compound acidic or non-acidic. Acids are substances which, upon dissociating with water, resulting in the production of Hydrogen ions. Some compounds show an acidic character as they dissociate in the aqueous solution, which results in the production of hydrogen ions (acids like HCl, HNO3). Compounds similar to glucose or alcohol do contain a hydrogen element, but they do not show
- ScienceClass 10CBSE
Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.
As the metal compound released is Calcium Chloride, the gas evolved here is CO2. Hence, metal A should be Calcium Carbonate. Hence, the reaction between Calcium Carbonate and HCl is CaCO3 (s) + 2HCl (Aq) → CaCl2( Aq) + CO2 (g) + H2O (l)
- ScienceClass 10CBSE
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?
Solution: When an acid reacts with any metal, salt and hydrogen gas are formed. Metal + Acid → Salt + Hydrogen gas
- ScienceClass 10CBSE
Why should curd and sour substances not be kept in brass and copper vessels?
Solution: Curd and sour food substances contain acids; these acidic substances combine with metal. This reaction turns food into poison, which damages people’s health.
- ScienceClass 10CBSE
You are given three test tubes. The three test tubes contain distilled water, an acidic solution and the basic solution, respectively. There is only red litmus paper available in order to identify what is there in each test tube. How will you find out what is in each of the test tubes?
Solution: We can identify the content in each of the test tubes using red litmus paper. This can be done by noticing the colour change of the red litmus paper. On litmus paper, the three solutions in the test tubes are poured separately. The solution which turns red litmus to blue contains a basic solution. Divide the formed blue litmus paper into two parts. The soluti