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 : 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 ? -Chemistry-10
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 : 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 : (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 : 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 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 : 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 : 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 : 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 : 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 : 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 : 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 : 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 : (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 : A metal X' acquires a green colour coating on its surface on exposure to air. (i) Identify the metal X' and name the process responsible for this change. (ii)Name and write chemical ... the green coating formed on the metal. (iii) List two important methods to prevent the process. -Chemistry
Last Answer : (i) Metal is copper. The process is corrosion. (ii)Basic copper carbonate [CuCO3.Cu(0H)2]. (iii) • It should be coated with tin • It should be mixed with other metals to form alloys.
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 : 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 : When a coordination compound CoCl3.6NH3 is mixed with AgNO3, 3 moles of AgCl are precipitated per mole of the compound. Write (i) Structural formula of the complex (ii) IUPAC name of the complex -Chemistry
Last Answer : i) Complex so formed is: CoCl3.6NH3 + AgNO3 → [Co(NH3)6]Cl3 (ii) IUPAC name of complex is: Hexaamminecobalt (III) chloride
Description : When a co-ordination compound CrCl3.6H2O is mixed with AgNO3, 2 moles of AgCl are precipitated per mole of the compound. Write (i) Structural formula of the complex. (ii) IUPAC name of the complex. -Chemistry
Last Answer : (i) The complex formed on mixing a coordination compound CrCl3.6H2O with AgNO3 is as follows CrCl3.6H2O + AgNO3 → [Cr(H2O5)Cl]Cl2. H2O (ii) Pentaaquachloridochromium (III) chloride monohydrate
Description : (i) Write down the IUPAC name of the following complex : [CO(NH3)5Cl]2+ (ii) Write the formula for the following complex : Potassium tetrachloridonickelate (II) -Chemistry
Last Answer : i) [CO(NH3)5Cl]2+ IUPAC name : Pentaammine chlorido cobalt (III) ion (ii) Formula of the complex potassium tetrachloridonickelate (II) K2[NiCl4]
Description : (i) Write down the IUPAC name of the following complex : [Cr(NH3)2CI3(en)]Cl (en = ethylenediamine) (ii) Write the formula for the following complex : Pentaamminenitrito-o-Cobalt (III) -Chemistry
Last Answer : (I) [Cr(NH3)2Cl3(en)]Cl IUPAC name : Diammine dichlorido ethylenediamine chromium (III) chloride. (ii) [Co(NH3)5(ONO)]2+
Description : What is observed when a solution of potassium iodide solution is added to a solution of lead nitrate? Name the type of reaction. Write a balanced chemical equation to represent the above chemical reaction. -Chemistry
Last Answer : Answer.Yellow precipitate of lead iodide is formed. It is precipitation reaction. Pb( NO3)2 (aq) + 2KI (aq) —-> Pbl2 (s) + 2KNO3 (aq) It is also called double displacement reaction.
Description : 13.a) What is solute and solvent in aerated drinks? b) Given a solution of substance 'A' how will you test whether it is saturated or unsaturated with respect to 'A' at the given temperature. -Chemistry
Last Answer : (a) No solute and solvent is available in aerated drinks. (b) in the given solution add small amount of solute A, if A dissolved a daydream a transparent solution is formed then it is an unsaturated solution and if A doesn't dissolved and a precipitate is formed then it's a saturated solution
Description : Write balanced equations for the reaction of: (i) aluminium when heated in air. Write the name of the product. (ii) iron with steam. Name the product obtained. (iii) calcium with water. Why does calcium start floating in water? -Chemistry
Last Answer : The bubbles of hydrogen stick to the surface of metal that is why it floats.
Description : Two substances, A and B were made to react to form a third substance, A2B according to the following reaction 2A + B → A2 B. Which of the following statements concerning this reaction are incorrect? -Chemistry 9th
Last Answer : (c) (i), (iii), (iv) Consider the example of H2O
Description : (a) Define a balanced chemical equation. Why should an equation be balanced? (b) Write the balanced chemical equation for the following reaction: (i) Phosphorus burns in presence of chlorine to form phosphorus penta chloride. (ii) Burning of natural gas. (iii) The process of respiration. -Chemistry
Last Answer : Answer. (a) Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical ... C6H12O6 (s) + 6O2 (g) + 6H2O ---> 6CO2 (aq) + 12H2O (l) + energy
Description : 2g of ferrous sulphate crystals are heated in a dry boiling tube. (i) List any two observations. (ii) Name the type of chemical reaction taking place. (iii) ‘Write the chemical equation for the reaction. -Chemistry
Last Answer : Answer. (i) •Green colour of Fe SO4 disappears and reddish brown solid is formed. • Smell of burning sulphur. (ii) Decomposition reaction
Description : Write the chemical equation of the reaction in which the following changes have taken place with an example of each: (i) Change in colour (ii) Change in temperature (iii) Formation of precipitate -Chemistry
Last Answer : (i)Cu (s) + 2AgNO3 (aq)———–> Cu(NO3)2(aq) + 2Ag The solution will become blue in colour and shiny silver metal will be deposited. (ii) NaOH + HCl ——&mdash ... )———–> Pbl2 (s) + 2KNO3 (aq) Yellow ppt Yellow precipitate of Pbl2will be formed.
Description : It is difficult to remember the formula of physics or the reaction of chemistry. What can I do ?
Last Answer : It is difficult to remember the formula of physics or the reaction of chemistry. What can I do ? প্রমাণ You need to know the evidence of these sources well. We all know ( a + b) 2 = a2 ... and put it in front of the table. The subconscious mind remembers things more. You can read these articles!
Description : A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further 18 g of water is added to this solution. The new vapour pressure ... K. Calculate (i) the molecular mass of solute and (ii) vapour pressure of water at 298 K -Chemistry
Last Answer : For a very dilute solution ∴ Molecular mass, MB = 34 g/mol.
Description : Write down the formula of : Tetraamineaquachloridocobalt(III) chloride. -Chemistry
Last Answer : [Co(NH3)4(H2O)Cl]Cl2
Description : (a) Write the essential condition for the following reaction to take place: 2AgBr--> 2Ag + Br2 Write one application of this reaction. (b) Complete the following chemical equation of a chemical ... science-5 (c) What happens when water is added to quick line. Write chemical equation. -Chemistry
Last Answer : Answer. This reaction is used in photography. (c) Slaked lime is formed with hissing sound and lot of heat is envolved.
Description : Study the following statements. (i) Hydraulic lime is suitable for white washing, (ii) Fat lime is suitable for whitewashing, (iii) Hydraulic lime is suitable for making mortar, (iv) Fat lime is suitable for making mortar.
Last Answer : Answer: Option B (B) (ii) and (iii)
Description : Classify the following mixtures as homogeneous and heterogeneous. (i)Tincture of iodine (iv)Sugar solution (ii)Smoke (iii)Brass -Chemistry
Last Answer : In the above classification, tincture of iodine, brass and sugar are homogenous mixture while the smoke is heterogeneous mixture. Tincture of iodine is a liquid solution, brass is an alloy made ... component. Smoke on other hand is composed of moisture and gas thus making the mixture heterogeneous.
Description : Gas X and Gas Y in solution state react to give a turns substance Z. X has unpleasant odour and turns lead acetate paper black. In the first reaction
Last Answer : Gas X and Gas Y in solution state react to give a turns substance Z. X has unpleasant odour and turns lead ... )Orarr` D. `SO_(2)+H_(2)O_(2)rarr`
Last Answer : Gas X and Gas Y in solution state react to give a turns substance Z. X has unpleasant odour and turns lead acetate ... 2)` C. `H_(2)S` D. `SO_(3)`
Last Answer : Gas X and Gas Y in solution state react to give a turns substance Z. X has unpleasant odour and turns lead acetate ... SO_(2)` D. `SO_(2) and O_(3)`
Description : To make a solution for filling radiator one bag of washing soda and 0.5 kg of kerosene oil should be added in water amounting a) 6 kg b) 8 k8 c ) 10 kg d) 12 kg
Last Answer : c ) 10 kg