Description : An iron nail is dipped in the solution of copper sulphate for about 30 minutes. State the change in colour observed. Give reason for the change. -Chemistry-10
Last Answer : When an iron nail is dipped in copper sulphate solution, the displacement reaction takes place. The colour of copper sulphate solution fades due to the formation of light green solution of iron sulphate.
Description : Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write two observations. -Chemistry
Last Answer : Answer. It is because displacement reaction takes place. Iron displaces copper from copper sulphate solution and forms pale green coloured solution of FeS04 and reddish brown copper metal gets deposited. Fe(s) + CuS04(aq) ——–> FeS04(aq) + Cu(s)
Description : Write the balanced equation for the following chemical reactions. (i) Hydrogen + Chlorine → Hydrogen chloride (ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride (iii) Sodium + Water → Sodium hydroxide + Hydrogen -Chemistry-10
Last Answer : (i) H2 + Cl2 → 2HCl (ii) 3 BaCl2 + Al2(SO4)3 → BaSO4 + 2 AlCl3 (iii) 2Na + 2H2O → 2NaOH + H2↑
Description : A solution of a substance ‘X’ is used for white washing. (i) Name the substance ‘X’ and write its formula. (ii) Write the reaction of the substance ‘X’ named in (i) above with water. -Chemistry-10
Last Answer : (i) The substance whose solution in water is used for white washing is calcium oxide (or quick lime). Its formula is CaO.
Description : What are metalloids? Explain by giving examples. -Chemistry-10
Last Answer : Metalloids are elements which show some properties of metals and some properties of non-metals. Examples: Silicon, boron, arsenic, antimony, germanium, tellurium, polonium.
Description : What happens when baking soda is heated? -Chemistry-10
Last Answer : Sodium hydrogen carbonate (also known as sodium bicarbonate or bicarbonate of soda) has the chemical formula NaHCO3. When it is heated above about 80°C it begins to break down, forming sodium carbonate, water and carbon dioxide. This type of reaction is called a thermal decomposition.
Description : Why is plaster of paris stored in a moisture proof container? -Chemistry-10
Last Answer : Plaster of Paris in contact with moisture (water) changes to solid hard mass, gypsum. Therefore, it gets wasted. Hence it should be stored in moisture proof containers.
Description : (i) Substances oxidised is Na as it gains oxygen and oxygen is reduced. (ii) Substances reduced is Cu as hydrogen is oxidised as it gains oxygen. -Chemistry-10
Last Answer : During this reaction, the sodium is gaining oxygen and is being oxidized. Oxygen is getting reduced. During this reaction, copper oxide is losing oxygen and is being reduced. The hydrogen is gaining oxygen and is being oxidized.
Description : Identify the substances that are oxidised and the substances which are reduced in the following reactions. (i) 4Na(s) + O2(g) → 2Na2O(s) (ii) CuO (s) + H2(g) → Cu (s) + H2O(l) -Chemistry-10
Last Answer : (i) Substances oxidised is Na as it gains oxygen and oxygen is reduced. (ii) Substances reduced is Cu as hydrogen is oxidised as it gains oxygen.
Description : Give an example of a double displacement reaction other than the one given in Activity 1.10 -Chemistry-10
Last Answer : Sodium hydroxide and hydrochloric acid react to form sodium chloride and water.
Description : Why is the amount of gas collected in one of the test tubes in text book Activity 1.7 (i.e., electrolysis of water) double of the amount collected in the other? Name this gas. -Chemistry-10
Last Answer : In Activity 1.7, water is electrolysed to give H2 gas at one electrode and O2 gas at the other electrode. 2H2O(l) → 2H2(g) + O2(g) Thus two molecules of water on electrolysis give two ... oxygen gas or in other words the amount of hydrogen gas collected would be double than that of oxygen gas.
Description : Write a balanced chemical equation with state symbols for the following reactions : -Chemistry-10
Last Answer : (i) BaCl2 (aq) + Na2SO4 (aq) → BaSO4(s) + 2NaCl (aq) (ii) NaOH (aq) + HCl(aq) → NaCl(aq) + H2O(l)
Description : Why should a magnesium ribbon be cleaned before burning in air ? -Chemistry-10
Last Answer : Magnesium gets covered with a layer of magnesium oxide when kept in air for a long time. This layer hinders the burning of magnesium. Hence, it is to be cleaned before burning.
Description : 15. An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the conve -Chemistry-10
Last Answer : Since, object-screen distance is double of object-lens separation, the object is at a distance of 2f from the lens and the image should be of the same size of the object.
Description : 14. An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the -Chemistry-10
Last Answer : Answer. hope this helps you
Description : 13. A ray of light, incident obliquely on a face of a rectangular glass slab placed in air, emerges from the opposite face parallel to the incident ray. State two factors on which the lateral displacement of the emergent ray depends. [Foreign] -Chemistry-10
Last Answer : Lateral displacement depends on the: angle of incidence, thickness of slab, and refractive index of the material. (any two)
Description : 12. Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed: -Chemistry-10
Description : 10. Which kind of mirrors are used in the headlights of a motor-car and why? [Foreign] -Chemistry-10
Last Answer : Answer. Concave mirror, to get the parallel beam of light.
Description : 11. Explain with the help of a diagram, why a pencil partly immersed in water appears to be bent at the water surface. [Delhi] -Chemistry-10
Last Answer : Answer. Light from different points on the pencil, immersed in water refracts and appears to come from a point above the original position.
Description : 7. Redraw the given diagram and show the path of the refracted ray: [All India(C)] -Chemistry-10
Description : 6. “The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of light? [Delhi] -Chemistry-10
Description : 5. The refractive indices of four media A, B, C and D are given in the following table: -Chemistry-10
Last Answer : (i) Minimum change is seen as light moves between 1.50 and 1.52, i.e. B and C. (ii) Maximum change when light moves between 1.33 and 2.40, i.e. A and D.
Description : 4. If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray. [Delhi (C)] -Chemistry-10
Last Answer : Answer. Ray NQ, as it has to be parallel to ray OS.
Description : 3. Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed: -Chemistry-10
Last Answer : Answer. Nature of image: Real, inverted and same size image is formed at the centre of curvature. Nature of image: Virtual, enlarged and erect image is formed behind the mirror. Nature of image: ... image: Virtual, erect and diminished image is formed between O and F on the same side of object.
Description : 2. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India] -Chemistry-10
Last Answer : this is the answer for the respected question
Description : 1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi] -Chemistry-10
Last Answer : Answer. hope this helps youu
Description : An iron nail is placed into some blue copper sulphate solution. A reaction takes place between the iron and the copper sulphate.?
Last Answer : Hdhdhrh
Description : What happens when? a) A cleaned iron plate or iron nail is kept in 10g of copper sulphate solution. b) A pinch of mercuric oxide is kept in a test tube. c)A small crystal of silver nitrate is dissolved in distilled water and a drop of ammonium hydroxide & a pinch of glucose powder are added.
Last Answer : a) A cleaned iron plate or iron nail is kept in 10g of copper sulphate solution. After a few hours a coating of copper is seen on iron nail/plate. It is based on displacement reaction. ... on the inner walls of the test tube. Aldehyde group in glucose reduced silver nitrate to metallic silver.
Description : 10.(a) An ore on treatment with dilute hydrochloric acid produces brisk effervesces. What type of ore is this? What steps will be required to obtain metal from the enriched ore. , (b) ... in coin and colour of the solution ? Write balanced chemical equation of the reaction involved. -Chemistry
Last Answer : (a) Carbonate ore: (i) Calcination: Carbonate ore is heated in limited supply of air and oxide is obtained, e.g. (b) Copper, being more reactive than silver will displace silver from silver nitrate ... and there will be deposition of silver on copper coin. The colour of solution will turn to blue.
Description : What happens when a iron nail or a piece of aluminium wire is dipped in concentrated nitric acid?
Last Answer : Iron nail or aluminium wire does not react with concentrated nitric acid. It makes iron more passive.
Description : When a spoon is to be electroplated with nickel the spoon is (1) dipped in a nickel sulphate solution (2) made anode and a pure nickel rod, the cathode (3) made cathode and a pure nickel red, the anode (4) coated with nickel sulphate and dried
Last Answer : made cathode and a pure nickel red, the anode
Description : (a) Write one example for each of decomposion reaction carried out with help of (i) Electricity (ii) Heat (iii) Light (b) Which of the following statements is correct and why copper can displace silver from silver nitrate and silver can displace copper from copper sulphate solution. -Chemistry
Last Answer : Thi is the Answer:
Description : What is the colour of ferrous sulphate crystals? How does this colour change after heating? -Chemistry
Last Answer : Answer.The colour of ferrous sulphate is pale green. The colour changes to reddish brown on heating due to formation of iron (III) oxide. Give an example each for ... reactions. Write relevant balanced chemical equations also. Thermal decomposition reaction: Photochemical decomposition reaction:
Description : What happens when zinc is dipped in a copper sulfate solution Zinc is higher on the activity series than copper.?
Last Answer : Zinc becomes plated with copper.
Description : In a solution of silver nitrate, a copper plate was dipped. After some time, silver from the solution was deposited on the copper plate. Which metal is more reactive – copper or silver?
Last Answer : More reactive metal displaces a less reactive metal. Hence copper metal is more reactive.
Description : Generally metallic oxides are basic and non-metallic are acidic in nature. Solution of which of the following oxides in water will change the colour of blue litmus to red? a)sulphur dioxide b)Magnesium oxide c)iron oxide d)copper oxide
Last Answer : a)sulphur dioxide
Description : Which of the following metals can deposit copper from copper sulphate solution? (1) platinum (2) Mercury (3) Iron (4) Gold
Last Answer : (3) Iron Explanation: The iron displaces copper from its salt, to make iron sulfate solution and deposit a thin coating of metallic copper on the surface of the metal. In general, any metal higher than copper in the "electromotive series" will displace copper from copper sulfate solution.
Description : Give reason: Iron displaces copper from copper sulphate solution.
Last Answer : Iron is more reactive than copper. Hence it displaces copper from copper sulphate solution.
Description : a few pieces of iron are dropped in a blue solution of copper sulphate?
Last Answer : A few pieces of iron are dropped into a blue coloured copper sulphate solution, it makes the blue colour of the solution fades and eventually turns it into green.
Description : Which of the following metals can deposit copper from copper sulphate solution ? (1) Platinum (2) Mercury (3) Iron (4) Gold
Last Answer : Iron
Description : What is the colour of copper sulphate?
Last Answer : Blue
Description : Above image shows an experiment where copper sulphate crystals are heated. When we heat the crystals, they turn white. If you moisten the crystals again with water you will find that colour of crystals reappears . (1 ... are present in one formula unit of copper sulphate (a)5 (b)2 (c)6 (d)7
Last Answer : (a)5
Description : What colour does methyl orange turn when dipped in a base?
Last Answer : What is the answer ?
Description : What colour does bromothymol blue turn when dipped in a base?
Description : Write the molecular formulae of: 1. Copper oxide 2. Iron (III) chloride 3. Sodium hydroxide 4. Iron (II) sulphide 5. Lead (II) oxide 6. Hydrogen nitrate (nitric ... Hydrogen sulphate (sulphuric acid) 8. Calcium hydroxide 9. Magnesium carbonate 10.Ammonium carbonate
Last Answer : 1. Copper oxide - CuO 2. Iron (III) chloride - FeCl3 3. Sodium hydroxide - NaOH 4. Iron (II) sulphide - FeS 5. Lead (II) oxide - PbO 6. Hydrogen nitrate (nitric acid) - HNO3 7. ... ) - H2SO4 8. Calcium hydroxide - Ca(OH)2 9. Magnesium carbonate - MgCO3 10.Ammonium carbonate - (NH4)2CO3
Description : Rohan had learnt that non-metals on beating with hammer are generally broken into pieces. Which of the following is a non-metal? a) iron nail b)aluminium wire c)copper wire d)piece of coal
Last Answer : d)piece of coal
Description : A student took Sodium Sulphate solution in a test tube and added Barium Chloride solution to it. He observed that an insoluble substance has formed. The colour and molecular formula of the insoluble substance is (a) Grey, Ba2SO4 (b) Yellow, Ba(SO4)2, (c) White, BaSO4 (d) Pink, BaSO4,
Last Answer : Answer: (c) White, BaSO4
Description : Why Magnesium , Copper and Zinc only react when dipped in hot water ?
Last Answer : Magnesium is the element at the top of the activation table. The value of its oxidation potential is more negative i.e. it is easily oxidized. But the position of copper is below H2 and the deposition ... in water to H2 gas. But magnesium degrades H + ions. So only magnesium reacts with hot water.
Description : Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives (1) Copper at eathode and oxygen at anode. (2) Copper at anode and oxygen at cathode. (3) Copper at cathode and anodes dissolve to give copper. (4) Hydrogen at cathode and oxygen at anode.
Last Answer : (1) Copper at eathode and oxygen at anode. Explanation: Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
Description : The metal used to recover copper from a solution of copper sulphate is?
Last Answer : Fe