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 : 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) What are fuel cells? Explain the electrode reactions involved in the working of H2 – O2 fuel cell. (b) Represent the galvanic cell in which the reaction Zn (s) + Cu2+ (aq) → Zn2+ (aq) + Cu (s) takes place. -Chemistry
Last Answer : (a) Fuel cells : These cells are the devices which convert the energy produced during combustion of fuels like H2, CH4, etc. directly into electrical energy. The electrode reaction for H2 – O2 fuel cell : (b) The galvanic cell may be represented as Zn (s) | Zn2+ (1M) || Cu2+ (1M) | Cu (s)
Description : CuO + H2 = Cu + H2O. This equation is an example of - (1) Oxidation (2) Decomposition (3) Reduction (4) Redox
Last Answer : (4) Redox
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 : 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 : 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 : Identify the type of reaction(s) in the following equations. (i)CH4 + 2O2 CO2 + 2 H2O (ii) Pb(NO3)2 + 2KI ——–>Pbl2 + 2KNOs (iii) CaO + H2O ——–> Ca(OH)2 (iv) CuSO4 + Zn ——–> ZnSO4 + Cu -Chemistry
Last Answer : Answer. (i) Combustion reaction and oxidation reaction. (ii)Double displacement reaction and precipitation reaction. (iii) Combination reaction. (iv) Displacement reaction.
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 : 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 : 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 : 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 : 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 : 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 : In the reaction, C6H12O6 + 6O2 6CO2 + 6H2O + energy, which component is → being reduced? A- O2 B- CO2 C- .H2O D- Energy
Last Answer : O2
Description : Copper substances when exposed to air gains a green coating due to the formation of: (1) CuO (2) CuCO3 Cu(OH)2 (3) CuSO4 (4) Cu(NO3)2
Last Answer : (2) CuCO3 Cu(OH)2 Explanation: When copper is exposed to air, it reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface and gains a green coat. This green substance is ... Cu(OH)2). The formation of this green coating on the surface of a copper object corrodes it.
Description : What sequence of coefficients will balance the following equation Na (s) plus O2 (g) 2Na2O (s).?
Last Answer : 4,1,2
Description : Sodium reacts with water to form sodium hydroxide and hydrogen gas. The balanced equation which represents the above reaction is (a) Na(s) + 2H20(l) → 2NaOH(aq) + 2H2(g) (b) 2Na(s) + 2H2O(l) → 2NaOH(aq) +H2(g) (c) 2Na(s) + 2H20(l) → NaOH(aq) + 2H2(g) (d) 2Na(s) + H20(l) - 2NaOH(aq) + 2H2(g)
Last Answer : Answer: (b)
Description : Cuo + c = what is the reaction in cu + co ?
Last Answer : The reaction is an oxidation reaction. This reaction is also called carbon deoxidation reaction.
Description : Acetaldehyde on treatment with Fehling's solution gives a precipitate of (a) Cu (b) Cu2O (c) CuO (d) None of these
Last Answer : Cu2O
Description : What information do you get from the following chemical equation: Zn(s) + 2HCl (dil) → ZnCl2 (aq) + H2(g)
Last Answer : This gives zinc chloride and hydrogen. The word equation is: Zinc + Hydrochloric acid → Zinc chloride + Hydrogen Formulae for the products are ZnCl2 and H2
Description : When volume of the equilibrium reaction C(s) + H2O(g) ⇌ CO(g) + H2(g) is increased at constant temperature the equilibrium will :
Last Answer : When volume of the equilibrium reaction C(s) + H2O(g) ⇌ CO(g) + H2(g) is increased at constant ... left c. be unaltered d. can not be predicted
Description : Which of the following reactions occuring during coal gasification is called the Neumann reversal reaction? (A) 2CO ↔ C + CO2 (B) CO + H2O ↔ CO2 + H2 (C) C + H2O ↔ CO + H2 (D) C + 2H2O ↔ CO2 + 2H2
Last Answer : (A) 2CO ↔ C + CO2
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 : What of the following reactions demonstrates a synthesis reaction A) Mg plus H2SO4 and gt MgSO4 plus H2 B) 2NaCl and gt 2Na plus Cl2 C) C plus O2 and gt CO2 D) Zn plus 2HCl and gt ZnCl2 plus H2?
Last Answer : C+O2 →CO2
Description : Which of the following chemical reactions will be favoured by low pressure? (A) 2HI ⇌ H2 + I2 (B) N2O2 ⇌ 2NO2 (C) N2 + O2 ⇌ 2NO (D) None of these
Last Answer : (B) N2O2 ⇌ 2NO2
Description : Two half-reactions of an electrochemical cell are given below : MnO-4 (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (I), E° = 1.51 V Sn2+ (aq) → Sn4+ (aq) + 2e- ... the redox equation from the standard potential of the cell and predict if the reaction is reactant favoured or product favoured. -Chemistry
Last Answer : The reactions can be represented at anode and at cathode in the following ways : At anode (oxidation) : Sn2+ → = Sn4+ (aq) + 2e- ] 5 E° = + 0.15 V At cathode (reduction) : MnO-4(aq) + 8H+ ... = E°cathode - E°anode = 1.51 - 0.15 = + 1.36 V ∴ Positive value of E°cell favours formation of product.
Description : Two half-reactions of an electrochemical cell are given below : MnO-4 (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (I), E° = 1.51 V Sn2+ (aq) → Sn4+ (aq) + ... -reactions and calculate the cell potential from the standard potentials and predict if the reaction is reactant or product favoured. -Chemistry
Last Answer : The reactions can be represented at anode and at cathode in the following ways : At anode (oxidation) : Sn2+ → Sn4+ (aq) + 2e- ] 5 E° = + 0.15 V Af cathode (reduction) : MnO-4(aq) + 8H+ ( ... = E°cathode - E°anode = 1.51 - 0.15 = + 1.36 V ∴ Positive value of E°cell favours formation of product.
Description : Which of the following statements about the given reaction are correct? 3Fe(s) + 4H2O(g) → Fe3O4 (s) + 4H2 (g) (a) Iron metal is getting oxidized. (b) Water is getting reduced. (c) Water is acting as reducing agent. (d)Water is acting as ... (B) & (C) B) (C) & (D) C) (A), (B) & (D) D) (B) & (D)
Last Answer : C) (A), (B) & (D)
Description : L.D. converter gas (produced in steel plant) comprises mainly of (A) CO (upto 65%) & CO2 (B) CO2 & H2 (C) CO & O2 (D) CO2 & O2
Last Answer : (A) CO (upto 65%) & CO2
Description : a) 110 g of salt is present in 550g of solution. Calculate the concentration of solution. b) 10 ml of H2SO 4 is dissolved in 90 ml of H2O. Calculate the concentration of solution. -Chemistry
Last Answer : The concentration of salt is determined by the division of mass of the solute by the mass of the solution and the percentage is obtained by multiplying the value by 100. The quotient of the division of 110 by 550 is 0.2 here. So after multiplying it with 100, it is 20%. So the concentration is 20%.
Description : The reaction A (l) → R(g) is allowed to reach equilibrium conditions in an autoclave. At equilibrium, there are two phases, one a pure liquid phase of A and the other a vapor phase of A, R and S. Initially A alone is present. The numbers of degrees of freedom are: (A) 1 (B) 2 (C) 3 (D) 0
Last Answer : (B) 2
Description : In the reaction 2Li(s)+2H2O(l) âž 2LiOH(aq)+H2(g), which compound is in the gaseous state?
Last Answer : H2
Description : If 48.0 g of O2 and 4.4 g of CO2 are placed in a 10.0 L container at 21c. what is the pressure of mixture of gases?
Last Answer : Need answer
Description : Assertion :- `H_(2)S+Cl_(2)rarr2HCl+S` In the above reaction, Cl has been oxidised to `Cl^(-)` while `S^(-2)` has been reduced to S Reason :- In a rea
Last Answer : Assertion :- `H_(2)S+Cl_(2)rarr2HCl+S` In the above reaction, Cl has been oxidised to `Cl^(-)` ... is False. D. If both Assertion & Reason are False.
Description : Entropy change of the reaction, H2O (liquid) → H2O (gas), is termed as the enthalpy of (A) Solution (B) Vaporisation (C) Formation (D) Sublimation
Last Answer : (B) Vaporisation