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De’s Foundation

ICSE Chemistry

QUESTIONS BASED ON PRACTICAL WORK 1.

Name a pale green powder which on heating turns black and gives off a gas which turns lime water milky. 2. A white powder is orange red when hot and yellow when cold, gives off a gas which has suffocating smell of burnt match and turns potassium dichromate paper from orange to green. (a) What is the name of the powder? (b) What is the effect on moist litmus when introduced into gas? (c) What is the name of the green substance? 3. Name a white powder which on heating turns yellow and when cold turns white again. There is no gas given off. 4. White powder given heating remains same and gives off a gas which turns lime water. Name the white powder. 5. A green hydrated salt on heating becomes anhydrous, white and amorphous. On heating more strongly it leaves a brown residue and gives a mixture of two gases. Write an equation for the reaction. 6. A red powder on heating turns chocolate brown, melts and effervesces to give a gas which relights a glowing splint. The residue is orange red when hot and yellow when cold. Name the compound and write an equation for the reaction. 7. A blue hydrate on heating becomes white amorphous. Name the powder and write an equation for the reaction. 8. A gas jar containing a hydride of an element is inverted over another gas containing an oxide of same element, to precipitate the element. Name the hydride and the oxide and write an equation for the reaction. 9. A reddish brown solid quickly becomes moist on exposure to air. When dissolved in water it gives a pale yellow solution. On adding sodium hydroxide to a portion of solution we obtain a reddish brown precipitate. On adding silver nitrate solution to a solution of the solid we obtain a thick curdy precipitate insoluble in dilute nitric acid but soluble in ammonium hydroxide solution. (a) Why does the solid become moist on exposure to air? (b) Name the reddish brown precipitate. (c) Why did the thick curdy precipitate not look white? (d) What is the anion and cation in the soluble of the powder? 10. On adding dilute hydrochloric to a black powder there is a brisk effervescence of gas. The gas turns lead acetate paper black. The solution that is formed is filtered. When sodium hydroxide is added to a solution of the powder, a dirty green precipitate is formed. (a) Name the black precipitate formed. (b) Name the other solution that would give the same precipitate. (c) Name the other solution which would give a different black precipitate. (d) What is the effect of bubbling the gas given off into a solution of potassium dichromate? (e) What is the cation in the powder? 11. A colourless gas when bubbled through a pale solution makes it dark brown. (a) Name the colourless gas. (b) Name the pale solution. (c) Name the dark brown substance. 12. A white powder is extremely soluble in water. The solution of the powder gives (a) a white precipitate with barium chloride solution. (b) A white precipitate with sodium sulphate solution. (c) A white precipitate with sodium hydroxide solution which is soluble in excess. 1. Name the white precipitate formed with barium chloride solution. 2. Name the white precipitate formed with sodium sulphate solution. 3. Name the white precipitate formed with sodium hydroxide solution. 4. Name the solution formed when the white precipitate in (3) dissolves in excess of sodium hydroxide. 13. A white powder is soluble in water. When a piece of magnesium is added to the solution, there is a vigorous effervescence of gas. When a burning splinter is brought to the mouth of the test tube there is a


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De’s Foundation

ICSE Chemistry

squeaky pop. The flame test is carried out with the powder. There is a persistent golden yellow flame. When barium chloride solution is added to a solution of the powder, a white precipitate is formed which is insoluble in dilute hydrochloric acid. (a) Name the white powder. (b) Name the gas given off. 14. Name the white precipitate formed with the barium sulphate. A mixture of two black powders on heating gives off a gas which turns lime water milky. On observing the residue we see red scales in the black residue. The residue partly dissolves in dilute sulphuric acid to form a pale blue solution. (a) What is the composition of the mixture? (b) Name the red scales. (c) Name the substance that would form on heating the blue precipitate. 15. X is a hydrated compound extremely soluble in water. The solution is alkaline to litmus. If dilute hydrochloric acid is added to the powder it gives a effervescence of gas which turns lime water milky. On dry heating the powder, it does not decompose but only becomes amorphous. Flame test carried out on the compound gives a persistent yellow colour. (a) What is X commonly called? (b) Name the phenomenon that gives the alkaline reaction with the solution of X. (c) Write a reaction that takes place when X is exposed to the air? (d) What is the phenomenon that occurs in (3)? 16. X is a mixture of two powders. The mixture is taken in a beaker. Water is added. The mixture is stirred and filtered. There is thick residue on the filter paper. The solution obtained is tested as follows. Sodium hydroxide solution id added to a portion of it. A white precipitate is formed which dissolves in excess of sodium hydroxide. Another portion of the solution is heated to the dryness. It is observed that the dry powder melts, gives off dense brown fumes of gas and leaves a white residue in the test tube. The residue on the filter paper is taken and divided into four portions. The 1st portion is treated with dilute hydrochloric acid. The 2nd portion is treated with dilute sulphuric acid. The residue does not dissolve in either of the two acids. The 3rd portion dissolves readily in dilute nitric acid and gives off a gas which turns lime water milky. The 4th portion on heating leaves a yellow residue. (a) Name the component of the mixture which is soluble in water. Give a reason for your answer. (b) Name component of the mixture which is insoluble in water. Give reasons for your answer. 17. A white powder is an anhydrous crystalate. On heating some of the powder in a dry test tube it gives dense white fumes which collect as a white solid on the cooler parts of the test tubes. When sodium hydroxide is added to the solution of the powder and warmed, it gives off a gas which turns moist red litmus blue. When silver nitrate is added to another portion of the solution, thick curdy white precipitate is formed. This does not dissolve in dilute nitric acid but dissolves in ammonium hydroxide solution. (a) Name the alkaline gas given off when the solution of the powder is treated with sodium hydroxide solution. (b)Give another test for the gas. (c) Name the cation of the powder. (d) Name the white sublimate formed. (e) Name the white precipitate formed when silver nitrate is added to a solution of the powder. (f)Name the anion in the powder. 18. A, B, C, D, E and F are all black powders. They are treated with hot concentrated hydrochloric acid A, B, C that gives off a gas which has a smell of rotten eggs. A gives a deep green solution. B gives a white crystalline precipitate on cooling. C gives a pale green solution. D does not give any effervescence of gas nor does it dissolve. E gives effervescence of gas which turns starch iodide paper black. F does not give any effervescence of gas but gives a deep green solution. Name the powders A to F. 19. X and Y are two solutions. When zinc is added to X and heated, there is a vigorous effervescence of gas which burns with a blue flame when a burning splint is brought near the gas. When zinc is added to Y and heated, there is a effervescence of the same gas. When ammonium chloride is added to both and warmed, Y gives an alkaline gas. There is no reaction with X. comment on the nature of X and Y. 20. A powder X is a mixture of a black compound (A) and a white compound (B). The mixture is warmed with concentrated sulphuric acid. A gas is given off which liberates iodine from potassium iodide. When


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De’s Foundation

ICSE Chemistry

treated with water the white powder dissolves. The black powder is insoluble. On filtration is treated with sodium hydroxide and warmed. A gas is given off which is bubbled trough copper sulphate solution. The solution first gives a precipitate and gives an intense blue solution. (a) Name the gas given off when the mixture is treated with concentrated sulphuric acid. (b) What would be the effect of exposing moist blue litmus paper to this gas? (c) What is the gas given off when a solution of B is warmed with sodium hydroxide? (d) What is the white powder? (e) What is the black powder? 21. A white powder on being treated with dilute HCL gives of a gas which has a strong suffocating smell of burnt match and turns potassium dichromate paper from orange to green. The solution of the powder formed after filtering is treated with sodium hydroxide solution. We get a white precipitate insoluble in excess of sodium hydroxide. Name (a) the gas given off (b) the anion of the powder. (c) the white precipitate formed. (d) the cation in powder. 22. A, B, C are three gases. They are all moist and several jars of each are available. When gas A is reacted with gas B, there is a fine deposit of the same yellow substance. When gas C is reacted with the gas B, there is a fine deposit of the same yellow substance. Gas A and gas B are both bleaching agents. A bleaches by oxidation and B bleaches by reduction. (a) Name the gases A, B and C. (b) Write a reaction of A with B and C with B. (c) Write a reaction that would take place between A and C. 23. A, X, B, Y are four compounds in a solution. X is an inorganic acid and B is a salt of an organic acid. When X is added to A and B we get the same white precipitate which is insoluble in dilute hydrochloric acid. When Y is added to A and B we get the same white precipitate that is soluble in heating. When X and Y are mixed a white precipitate is formed which is insoluble in dilute hydrochloric acid. Identify A, X, B and Y. 24. W, X, Y and Z are four solutions. When Z is added in turns to W, X and Y, W and X give a white precipitate that is soluble in excess of Z. Y does not give a precipitate but on warming it gives off an alkaline gas. When Y is added to W and X, there is no reaction with X but W gives a white precipitate which dissolves on heating. Name (a) The cations in W and X. (b) The cation and anion in Y. (c) The anion in Z. 25. P, Q, R and S are four soluble compounds. When S id added to R, there is a yellow Precipitate that dissolves on heating. When Q is added to R there is a white precipitation That does not dissolves in dilute hydrochloric acid. When P is added to R there is a white precipitate which is insoluble in dilute HCL. Name (a) the cation and anion in R. (b) the cation abd anion in Q. (c) anion in S. (d) the anion in P.

QUESTION BASED ON PRACTICAL /ANALYTICAL CHEMISTRY  

PRACTICAL CHEMISTRY