Chemical Reaction and Acid Bases and Salts Important Questions

Chemical Reaction and Acid Bases and Salts Important Questions is the unit  of Science of Class 10 CBSE consist of Year wise 2018 to 2024 topic and chapter wise  questions

CHEMICAL REACTION

1. a)*Iron III oxide reacts with Aluminum and gives iron and aluminum oxide. write the balance equation it is also reduced b)dil H2SO4 reacts with  Al powder c) dil HCl react with Na2CO3 d)*  CO2 passes through lime water. e) NaOH solution  is heated with Zn f) dil H2SO4 react with Na2CO3 g)egg shell (CaCO3) react with dil HCl  h) copper II oxide react  with dil HCl. i)Calcium metal is reacted with water  j)Cinnabar (HgS) is heated in presence of air  k)* MnO2 is heated  with aluminum powder l)The compound obtained on reaction of iron and steam. m) Mercury oxide is heated n) mixture of cuprous oxide and  cuprous sulphide is heated
2. A reddish brown  coloured metal ,used in electric wire   when powdered and heated becomes black ,when H2 gas is passed over it it regains it’s original colour  on the basis of explanation   a) name the metal  and black colour substance  write the  balanced equation
3.  Identify the types of reactions  .a) CH4 +2O2 —-> CO2 + 2H2O
4. Pb(NO3)2 + 2KI ——-.> PbI2 + 2 KNO3
5. ***CaO +H2O ———> Ca(OH)2 + heat
6. *CuSO4 +Zn ———> ZnSO4 + Cu .
7. AgNO3 (aq) + NaCl (aq) ———> AgCl (s) + NaNo3 (aq)
8. 2KClO3 ———-> 2KCl + 3O2
9. CaCO3 +H2O + CO2 ——–>
10. HCl +H2O ———>
11. BaCl2 + H2SO4 ———>BaSO4  (white ppt)+ 2 HCl
12. why the blue colour of copper sulphate disappears when some aluminum power is added to it .
13. When calcium oxide is taken in container and water is added to it slowly  state two observation made the experiment and write the balanced equation  a) kind of sound b) exothermic / endothermic reaction. (2024)
14. * when  H2 gas is passed over heated copper II oxide  , copper and steam is formed  write the equation write the substance oxidised and reduced .
15. A student dropped  a few pieces of marble in dil HCl in the test tube the gas evolved passed through lime water .write the balanced equation .

11     write which of following  substances are oxidise / reduced

3MnO2+4Al ——-> 3Mn +2Al2O3  ;

Fe2O3 +3CO ——–> 2Fe + 3CO2

SO2 +2H2S ———–>3S + 2H2O

* MnO2 +4HCl ———> MnCl2 +2H2O+Cl2

12. What is corrosion and rancidity , oxidation and reduction,

13. In the electrolysis of water why the volume of gas collected over one electrode is double that of gas collected over another .name the gases  on which electrode are they collected

14**What type of reaction is it write the balanced equation when lead nitrate is reacted with potassium iodide ./ Znic react wit silver nitrate to produce znic nitrate and silver.

15 * Write the balanced equation when solution of Barium chloride and Sodium sulphate in water react to give insoluble barium sulphate and solution of sodium chloride. Name the type of reaction what name is given to insoluble substances.(2024)

16 Decomposition reaction requires energy either in form of heat/ light/electricity write  thermal decomposition of CaCO3 ,Ag Cl ,H2O

17. 2ml of NaOH solution  is added to a few  pieces of Zn granules in a test tube when the content is warmed a gas evolved which is bubbled through soap solution before testing . write the equation named the gas  test to detect the gas  .What happens the same metal is reacted with  strong dil acid.

18. When  H2S  gas is passed through a blue colour solution of copper sulphate a clack precipitate of copper sulphide is obtained and sulphuric acid is obtained  this reaction is rhe example of ————— reaction.

important question 2024

When 2 ml of sodium hydroxide solution is added to few pieces of Znic  granulated in a test tube and than warmed the reaction occurs :

Ans : 2NaOH +Zn ——->Na2ZnO2 (sodium Zincate) +H2 

The decomposition reaction in which source of energy is light

Ans  : 2AgBr ——-sunlight —–>  2Ag + Br2 ( see notes  for more examples )

3. Consider the compounds  with maximum number of water of crystallisation

FeSo4 , CuSO4 , CaSO4 and Na2SO4

Ans : Washing Soda Na2SO4 . 10 H2O , Green Vitriol FeSO4 .7H2O, blue Vitriol CuSO4 .5H2O, Gypsum CaSO4.2H2O

4.MnO2 +4HCl ———> MnCl2 + 2H2O +Cl2 the reaction given is redox reaction  because

Ans: MnO2 is reduced and HCl is oxidized

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ACID BASES AND SALT

1. A solution turns red litmus blue its pH value may be 1,4,5,10
2. A solution react with crushed egg shell to give a gas that turns lime water milky. The solution contains HCl or NaCl
3. Which  medicine is used for the treatment of indigestion.
4. What happens when a solution of acid react with the solution of base in a test tube i) salt is formed ii)temperature of solution decreases iii ) temperature of solution  rises.
5.  As aqueous solution turns red litmus  blue  excess addition of  which solution will reverse the change  i) baking Soda ii)HCl
6. During the preparation of HCl gas why is it passed through CaCl2  .
7.  Give the formula of  Baking Soda, Blue vitriol ,washing soda , Gypsum
8. Sodium carbonate is basic salt because it is  i)strong acid and weak base ii) weak acid and strong base
9. Calcium phosphate is present in tooth enamel is acidic /basic.
10. Change of pH paper yellow orange changes to green blue can either be antacid /common salt/vinegar.
11. If a few drops of concentrated acid spills over the hand the student  wash the hand with the saline or wash the hand of plenty of water and put the paste of NaHCO3.
12. Sodium hydrogen carbonate when added to acetic acid evolve  gas i) turns lime water milky  ii) it extinguishes a burning splinter iii) it dissolves in the solution of NaOH  iv) it has a pungent smell select the option.
13. One of the constituents of baking powder is NaHCO3 other one is HCL/Tartaric acid
14.  Which statement is correct  a) higher the pH stronger the acid  b) higher the pH weaker the acid  c) lower the pH  stronger the base   d) lower the pH weaker the base
15.  The pH value of gastric juice  released during digestion is more than7 or less than 7
16.  Name the phenomena when small amount of acid is added to water a)ionization and neutralization b)Dilution and Neutralization c)ionization and dilution
17. Which of the following  can be used as acid -base indicator by visually impaired students  a) turmeric b) Vanilla essence c) litmus
18. CO2 gas is not produced on the treatment of following with dilute acid  a) Marble b) Limestone  c)baking soda d) lime  (CaO)
19. Lime juice/lime water which contain acid.
20. By demonstrating the electrical conductivity through electrolyte a) the bulb glows  because NaOH is strong base and produce ions for conduction  b)blub will not glows as electrolyte is not acid fig
21. Onion, clove and Vanilla is a kind of _________ indicators
22.  Which is correctly matched i)acid +salt ——–Metal +H2  ii)Acid +Metal carbonate ——-> salt +CO2+H2O    iii) Metal oxide + acid ——-> Salt +water
23. Which is correct a)adding acid to water by stirring b) adding water to acid by stirring.
24. Which of the statements are correct  for pH scale a)A scale for measuring hydronium ion concentration  b)Values less than 7 represent acidic medium c)as pH increases from 7 to 14  it represent increase in hydrogen ion.
25.  Which  statements are correctly matched a)pH of plants and animals lies 7 -7.8 b)pH of rain water is  7.6  c) Tooth decay when pH is 5.5 d) common salt is forrmed by NaOH and HCl e)Brine is aqueous solution of NaCl  f)Chlor – alkali process is used for the formation of NaCl.
26.  Formula of plaster of Paris_______
27.  Which is responsible of acid rain a)H2S and CO2 b)oxides of Sulphur and nitrogen  c) oxides of Sulphur and CO2
28. On washing clothes with soap a turmeric stain on cloth turns red because soap is acidic /alkaline
29.  Assertation : Olfactory indicators are those whose colour changes in  acidic medium           Reason :They react with acidic and basic  solution             ANS  both are false as olfactory indicators whose colour changes inacdicas wel as basic media .
30. Assertation :Active metal react with acid to give hydrogen  REASON ;It is the example of displacement reaction        ANS; Both are true
31.  Assertation :Acids contain H+ ion     REASON : H+ ion naturalize acid                                 ANS :assertation is true but reason is wrong.
32. Assertation : the process of dissolving acid or base in water is highly exothermic                    Reason :A large amount is produced              ANS ; Both are true.
33.  Assertation: On heating the colour of hydrated copper sulphate changes from blue to white      REASON : Copper sulphate is a crystalline salt.                                                                 ANS Both are correct
34.  which is HCL or acetic acid is  strong acid why?
35. Write the equation of a)dissociation of HCl in water b)formation of hydronium ions  c) NaOH/KOH dissolved in water.
36.  Name the acids present in  a) Vinegar  b)sour milk c) orange   d) lemons
37. The enamel of tooth is the hardest substances in the body  how it gets damage while eating sweets.
38.  Name the gas produced when metal is reacted with dil. H2SO4  how will you test tge gas  evolved.
39. Calcium compound which is yellowish  white powder usedas disinfectant and also in textile industry. Which gas is released on its preparation  name the compound and write the preparation with balanced equation.
40. A metal compound react with dil H2SO4 produce the gas which extinguish the burning candle  name the gas and write the equation.
41.  Give only  one word for the statements a) water soluble base b) a substance which dissociates on dissolving in water gives hydrogen ions  c) a reaction between acid and base to give salt and water d) a substance produce OH- ion on dissolving in water.
42. The soil  field is highly acidic what minerals should be mixed to reduce the acidity
43. What is the effect on litmus paper in aqueous solution of NaCl and NaOH and why ?
44. Explain why an aqueous  solution of NaSO4 is neutral whereas Na2CO3 is basic.
45.  Why milkman add baking soda in fresh milk in very small amount  why does shit the pH  to alkaline and why does this milk take long time to make curd.
46. A compound X is used in making Pakoras in kitchen .It is also used to remove indigestion. identify  X what happens when heated. name the gas produced and which substance is added to make the cake spongy.
47. How is plaster of Paris is prepared why is it stored in moist proof containers.?
48. Why happens to anhydrous  CuSO4 when few drops of water falls on it ?
49.  What happens when Zn is treated with NaOH write the equation.?
50. What happens when base react with non-metals. ?
51.  Why do acid do not show acidic character in absence of water .?
52.  Write the uses of  NaOH ,Chlorine  which is produced in  Chlor – Alkali process  name other by products
53. how will you prepare washing soda explain with equation and uses
54. Illustrate  any three chemical properties of acids with examples.
55. what happens to blue litmus when added to soda water.?,why common salt becomes sticky during rainy season, ?Why CaCl2 used as desiccator.?
56. A tarnish copper vessel shine when rubbed by lemon why? why all alkali are base butall bases are not alkali  Why do we apply mild base on the sung of honey bee which acid do they release.
57. The pH value of Tomato Juice is 4.6 How it is likely to taste  Justify yr answer? How weak and strong acids are different in the ion formation in aqueous solution .? Why is acid rain dangerous for aquatic animals and plants . (2024)