A fuel is that substance which, on combustion can provide sufficient energy in a convenient form for sustained use over a long period of time. Two important characteristics of a good fuel are: (i) The fuel is available easily at an economic price and can be conveniently transported and stored. (ii)Read more
A fuel is that substance which, on combustion can provide sufficient energy in a convenient form for sustained use over a long period of time.
Two important characteristics of a good fuel are:
(i) The fuel is available easily at an economic price and can be conveniently transported and stored.
(ii) What is the amount and rate of release of heat energy by the fuel on burning and whether any smoke is produced or not.
(i) Medha wants to segregate biodegradable and non-biodegradable waste so that these can be properly and safely disposed of without causing any harm to environment and ecology. (ii) Medha is a conscientious student who believes that our environment must remain clean and non-polluted and all of us caRead more
(i) Medha wants to segregate biodegradable and non-biodegradable waste so that these can be properly and safely disposed of without causing any harm to environment and ecology.
(ii) Medha is a conscientious student who believes that our environment must remain clean and non-polluted and all of us can live healthy.
(iii) Medha will use biodegradable waste to produce biogas or compost mannure.
When a circular coil of N tums is placed vertically in east-west direction and a current is passed through it, the magnetic field at the centre of coil points horizontally along north-south direction. The magnetic compass needle placed there was already pointing in north-south direction' Hence thereRead more
When a circular coil of N tums is placed vertically in east-west direction and a current is passed through it, the magnetic field at the centre of coil points horizontally along north-south direction. The magnetic compass needle placed there was already pointing in north-south direction’ Hence there is no deflection shown by the magnetic needle’ When the coil is turned through 90° about a vertical axis, the coil is now in north-south direction and magnetic field due to current is along east-west direction horizontally. As a result the magnetic needle shows deflection. When the coil is further turned through 90° it again lies in east-west direction vertically and magnetic field due to current flow in the coil is along north-south horizontally. Hence, the magnetic needle remains in its equilibrium position and shows no deflection.
In multicellular organisms, the body size is large and diffusion pressure alone is not enough to carry food, exchange gases or remove wastes. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs. Thus, mulRead more
In multicellular organisms, the body size is large and diffusion pressure alone is not enough to carry food, exchange gases or remove wastes. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs. Thus, multicellular organisms have developed various organs/organ systems for transportation of gases, wastes, food etc., like blood in animals or xylem and phloem in plants etc.
Double circulation occurs in humans. It refers to the passage of same blood twice through the heart. The right side receives deoxygenated blood whereas the left chambers of the heart pump oxygenated blood. There is no intermixing of oxygenated and deoxygenated blood. The oxygenated blood from lungsRead more
Double circulation occurs in humans. It refers to the passage of same blood twice
through the heart. The right side receives deoxygenated blood whereas the left chambers of the heart pump oxygenated blood. There is no intermixing of oxygenated and deoxygenated blood. The oxygenated blood from lungs comes to left auricle through pulmonary veins. Simultaneously, the deoxygenated blood comes to right auricle through two large veins Contraction of ventricles results in transfer of blood from them into lungs and various body parts. Precisely left ventricle on contraction sends oxygenated blood to body through the largest
artery Aorta. While the right ventricle pumps the blood into lungs and for oxygenation through pulmonary artery. The separation of the right side and left side of the heart is useful so as to prevent oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, Which constantly use the energy to maintain their body temperature.
Relation between oxidation and oxidising agent: Addition of oxygen or removal of hydrogen is called oxidation. The substance that brings about oxidation is called oxidising agent. Example: Fe₂O₃ + 2Al ⟶A1₂O₃ + 2Fe In this example, Fe₂O₃ has acted as oxidising agent and A1 has been oxidised.
Relation between oxidation and oxidising agent:
Addition of oxygen or removal of hydrogen is called oxidation.
The substance that brings about oxidation is called oxidising agent.
Example: Fe₂O₃ + 2Al ⟶A1₂O₃ + 2Fe
In this example, Fe₂O₃ has acted as oxidising agent and A1 has been oxidised.
(i) When Zinc carbonate is calcined : ZnCo₃ ⟶ ZnO + CO₂↑ (ii) When manganese dioxide is heated with aluminum powder: 3MnO₂ + 4A1 ⟶ 3Mn + 2A1₂O₃ (iii) When magnesium is heated with very dil. HNO₃: Mg + 2HNO₃ ⟶ Mg(NO₃)₂ + H₂
(i) When Zinc carbonate is calcined :
ZnCo₃ ⟶ ZnO + CO₂↑
(ii) When manganese dioxide is heated with aluminum powder:
3MnO₂ + 4A1 ⟶ 3Mn + 2A1₂O₃
(iii) When magnesium is heated with very dil. HNO₃:
Mg + 2HNO₃ ⟶ Mg(NO₃)₂ + H₂
(i) Phenolphthalein gives a pink colour with soap because soap contains alkali in traces. (ii) By-products of chlor-alkali Process: NaOH, H ₂ and C1₂ (iii) Universal indicator specifies the various levels of H+ concentration.
(i) Phenolphthalein gives a pink colour with soap because soap contains alkali in traces.
(ii) By-products of chlor-alkali Process:
NaOH, H ₂ and C1₂
(iii) Universal indicator specifies the various levels of H+ concentration.
Quicklime reacts with water to form slaked lime (lime water). It is an exothermic reaction. That is why the container became hot. CaO + 2H₂O ⟶ Ca(OH)₂ + Heat When calcium hydroxide is applied on the wails, it reacts with atmospheric carbon dioxide to form calcium carbonate which gives a shining whitRead more
Quicklime reacts with water to form slaked lime (lime water). It is an exothermic reaction. That is why the container became hot.
CaO + 2H₂O ⟶ Ca(OH)₂ + Heat
When calcium hydroxide is applied on the wails, it reacts with atmospheric carbon dioxide to form calcium carbonate which gives a shining white coating on the walls.
Ca(OH) ₂ + CO₂ ⟶ CaCO₃ + H₂O
(a) Name one salt each of the following types: (i) which gives acidic solution in water. (ii) which gives alkaline solution in water. (iii) which gives neutral solution in water. (b) Name one natural source of each of the following acids: (i) Citric acid (ii) Oxalic acid (iii) Lactic acid (iv) Tartaric acid (v) Acetic acid.
(a) (i) Ammonium chloride (ii) Sodium acetate (iii) Sodium chloride. (b) (i) Citric acid - Orange (ii) Oxalic acid - Tomato (iii) Lactic acid - Sour milk (curd) (iv) Tartaric acid - Tamerind (v) Acetic acid - Vinegar.
(a) (i) Ammonium chloride
See less(ii) Sodium acetate
(iii) Sodium chloride.
(b) (i) Citric acid – Orange
(ii) Oxalic acid – Tomato
(iii) Lactic acid – Sour milk (curd)
(iv) Tartaric acid – Tamerind
(v) Acetic acid – Vinegar.
Define fuel. List any two characteristics that you would look for in a good fuel.
A fuel is that substance which, on combustion can provide sufficient energy in a convenient form for sustained use over a long period of time. Two important characteristics of a good fuel are: (i) The fuel is available easily at an economic price and can be conveniently transported and stored. (ii)Read more
A fuel is that substance which, on combustion can provide sufficient energy in a convenient form for sustained use over a long period of time.
See lessTwo important characteristics of a good fuel are:
(i) The fuel is available easily at an economic price and can be conveniently transported and stored.
(ii) What is the amount and rate of release of heat energy by the fuel on burning and whether any smoke is produced or not.
Medha is the Eco-club prefect of her school. She knows about one school being a zero-garbage zone. She showed her willingness to her teachers to do the same in her school. She decided to put different coloured dust bins for segregating biodegradable and non-biodegradable garbage as the first step. Now answer the following questions: (i) why does Medha want to segregate biodegradable and non-biodegradable waste? (ii) State the values that prompted that action of Medha. (iii) What can Medha do with the biodegradable waste ?
(i) Medha wants to segregate biodegradable and non-biodegradable waste so that these can be properly and safely disposed of without causing any harm to environment and ecology. (ii) Medha is a conscientious student who believes that our environment must remain clean and non-polluted and all of us caRead more
(i) Medha wants to segregate biodegradable and non-biodegradable waste so that these can be properly and safely disposed of without causing any harm to environment and ecology.
See less(ii) Medha is a conscientious student who believes that our environment must remain clean and non-polluted and all of us can live healthy.
(iii) Medha will use biodegradable waste to produce biogas or compost mannure.
A circular coil of N turns is placed vertically with its plane in east-west direction. A magnetic compass needle is placed at the centre of the coil. Will the magnetic needle show any deflection when current is passed through the coil? How will the deflection change as we turn the coil at 90° about a vertical axis keeping the magnetic needle fixed? What would happen to the deflection if the coil is further rotated through 90°?
When a circular coil of N tums is placed vertically in east-west direction and a current is passed through it, the magnetic field at the centre of coil points horizontally along north-south direction. The magnetic compass needle placed there was already pointing in north-south direction' Hence thereRead more
When a circular coil of N tums is placed vertically in east-west direction and a current is passed through it, the magnetic field at the centre of coil points horizontally along north-south direction. The magnetic compass needle placed there was already pointing in north-south direction’ Hence there is no deflection shown by the magnetic needle’ When the coil is turned through 90° about a vertical axis, the coil is now in north-south direction and magnetic field due to current is along east-west direction horizontally. As a result the magnetic needle shows deflection. When the coil is further turned through 90° it again lies in east-west direction vertically and magnetic field due to current flow in the coil is along north-south horizontally. Hence, the magnetic needle remains in its equilibrium position and shows no deflection.
See lessIn single celled organisms diffusion is sufficient to meet all their requirements of food exchange” of gases or removal of wastes but it is not in case of multicellular organisms Explain the reason for this difference.
In multicellular organisms, the body size is large and diffusion pressure alone is not enough to carry food, exchange gases or remove wastes. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs. Thus, mulRead more
In multicellular organisms, the body size is large and diffusion pressure alone is not enough to carry food, exchange gases or remove wastes. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs. Thus, multicellular organisms have developed various organs/organ systems for transportation of gases, wastes, food etc., like blood in animals or xylem and phloem in plants etc.
See lessDescribe double circulation in human beings. why is it necessary?
Double circulation occurs in humans. It refers to the passage of same blood twice through the heart. The right side receives deoxygenated blood whereas the left chambers of the heart pump oxygenated blood. There is no intermixing of oxygenated and deoxygenated blood. The oxygenated blood from lungsRead more
Double circulation occurs in humans. It refers to the passage of same blood twice
See lessthrough the heart. The right side receives deoxygenated blood whereas the left chambers of the heart pump oxygenated blood. There is no intermixing of oxygenated and deoxygenated blood. The oxygenated blood from lungs comes to left auricle through pulmonary veins. Simultaneously, the deoxygenated blood comes to right auricle through two large veins Contraction of ventricles results in transfer of blood from them into lungs and various body parts. Precisely left ventricle on contraction sends oxygenated blood to body through the largest
artery Aorta. While the right ventricle pumps the blood into lungs and for oxygenation through pulmonary artery. The separation of the right side and left side of the heart is useful so as to prevent oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, Which constantly use the energy to maintain their body temperature.
State the relationship between oxidation and oxidising agent in a redox reaction. Give an example of redox reaction showing the relationship between oxidation and oxidising agent.
Relation between oxidation and oxidising agent: Addition of oxygen or removal of hydrogen is called oxidation. The substance that brings about oxidation is called oxidising agent. Example: Fe₂O₃ + 2Al ⟶A1₂O₃ + 2Fe In this example, Fe₂O₃ has acted as oxidising agent and A1 has been oxidised.
Relation between oxidation and oxidising agent:
See lessAddition of oxygen or removal of hydrogen is called oxidation.
The substance that brings about oxidation is called oxidising agent.
Example: Fe₂O₃ + 2Al ⟶A1₂O₃ + 2Fe
In this example, Fe₂O₃ has acted as oxidising agent and A1 has been oxidised.
Write chemical equations for the following reactions: (i) When zinc carbonate is calcined. (ii) When manganese dioxide is heated with aluminium powder. (iii) When magnesium is treated with very dilute nitric acid.
(i) When Zinc carbonate is calcined : ZnCo₃ ⟶ ZnO + CO₂↑ (ii) When manganese dioxide is heated with aluminum powder: 3MnO₂ + 4A1 ⟶ 3Mn + 2A1₂O₃ (iii) When magnesium is heated with very dil. HNO₃: Mg + 2HNO₃ ⟶ Mg(NO₃)₂ + H₂
(i) When Zinc carbonate is calcined :
See lessZnCo₃ ⟶ ZnO + CO₂↑
(ii) When manganese dioxide is heated with aluminum powder:
3MnO₂ + 4A1 ⟶ 3Mn + 2A1₂O₃
(iii) When magnesium is heated with very dil. HNO₃:
Mg + 2HNO₃ ⟶ Mg(NO₃)₂ + H₂
Answer the following questions: (i) State the colour of phenolphthalein in soap solution. (ii) Name the by-product of chlor-alkali process which is used for the manufacture of bleaching powder. (iii) Name one indicator which specifies the various levels of H⁺ ion concentration.
(i) Phenolphthalein gives a pink colour with soap because soap contains alkali in traces. (ii) By-products of chlor-alkali Process: NaOH, H ₂ and C1₂ (iii) Universal indicator specifies the various levels of H+ concentration.
(i) Phenolphthalein gives a pink colour with soap because soap contains alkali in traces.
See less(ii) By-products of chlor-alkali Process:
NaOH, H ₂ and C1₂
(iii) Universal indicator specifies the various levels of H+ concentration.
Rama wanted her house to be whitewashed. She bought some quicklime from the market and dissolved it in water in a big tub. She noticed that the container became hot without any heating. Give reason for her observation with equation and name the product formed. What happens when it is applied on the walls?
Quicklime reacts with water to form slaked lime (lime water). It is an exothermic reaction. That is why the container became hot. CaO + 2H₂O ⟶ Ca(OH)₂ + Heat When calcium hydroxide is applied on the wails, it reacts with atmospheric carbon dioxide to form calcium carbonate which gives a shining whitRead more
Quicklime reacts with water to form slaked lime (lime water). It is an exothermic reaction. That is why the container became hot.
See lessCaO + 2H₂O ⟶ Ca(OH)₂ + Heat
When calcium hydroxide is applied on the wails, it reacts with atmospheric carbon dioxide to form calcium carbonate which gives a shining white coating on the walls.
Ca(OH) ₂ + CO₂ ⟶ CaCO₃ + H₂O