Distinction between kilowatt and kilowatt hour: kilowatt:- 1. It is a unit of electrical Power. 2. Power in kW = V(volt) x l(ampere)/1000 kilowatt hour:- 1. It is a unit of electrical energy. 2. Energy in kw h = v(volt)x l(ampere) x t(hour)/1000 As the heater is rated 4'4kW;220 V, hence (i) CurrentRead more
Distinction between kilowatt and kilowatt hour:
kilowatt:- 1. It is a unit of electrical Power.
2. Power in kW = V(volt) x l(ampere)/1000
kilowatt hour:- 1. It is a unit of electrical energy.
2. Energy in kw h = v(volt)x l(ampere) x t(hour)/1000
As the heater is rated 4’4kW;220 V, hence
(i) Current drawn by the heater t = P/V = 4.4KW/220V = 4.4 x 1000W /220V = 20A
(ii) Resistance of the heater element R = V/I = 220V/20A = 11Ω
(iii) Energy consumed by the heater in 5 hours E =Pt = 4.4 kW x 5 h = 22 kw h
(iv) Cost of running the heater @ ₹ 6.50 per kw h=22 x ₹ 6.50 = ₹ 143
(a) When an acid reacts with a base, formation of salt and water takes place. This is called neutralisation reaction. For example, sodium hydroxide reacts with hydrochloric acid as under: NaOH + HC1 ⟶ NaC1 + H₂O (b) (i) Citric acid - Lemon (ii) Lactic acid - Sour milk (curd) (iii) Marble is calciumRead more
(a) When an acid reacts with a base, formation of salt and water takes place. This is called neutralisation reaction. For example, sodium hydroxide reacts with hydrochloric acid as under:
NaOH + HC1 ⟶ NaC1 + H₂O
(b) (i) Citric acid – Lemon
(ii) Lactic acid – Sour milk (curd)
(iii) Marble is calcium carbonate. Marble reacts with dilute hydrochloric acid to evolve carbon dioxide gas which when passed through lime water turns it milky. The reactions are as under:
CaCO₃ (s) + 2HCl (aq) ⟶CaC1₂ (aq) + CO₂ (g) + H₂O (1)
Ca(OH)₂ + CO₂ ⟶ CaCO₃ + H₂O
The gas evolved is carbon dioxide. Lime water will become milky.
(a) A mixture of two metals or a metal and a non-metal in a definite proportion is called alloy. Advantages of making alloys: (i) For making machinery parts. (ii) For making jewellery. (b) (i) Copper and aluminium are good conductors of electricity. Therefore, their wires are used for electricity trRead more
(a) A mixture of two metals or a metal and a non-metal in a definite proportion is
called alloy.
Advantages of making alloys:
(i) For making machinery parts.
(ii) For making jewellery.
(b) (i) Copper and aluminium are good conductors of electricity. Therefore, their wires are used for electricity transmission.
(ii) Iron gets rusted by reaction with atmospheric oxygen and moisture. By painting frequently, iron grill is prevented from getting rusted.
LPG is considered an ideal fuel on account of the following reasons: (i) The LPG has a large calorific value i.e., burning of even small quantity of LPG produces a large amount of heat energy. Thus, it is economical. (ii) It burns completely without any odour and leaves no residue. (iii) h is convenRead more
LPG is considered an ideal fuel on account of the following reasons:
(i) The LPG has a large calorific value i.e., burning of even small quantity of LPG produces a large amount of heat energy. Thus, it is economical.
(ii) It burns completely without any odour and leaves no residue.
(iii) h is convenient to use and easy to transport and store’
(i) So1ar energy and biomass energy- are two sources of energy which are considered as best form of energy from the environmental consequences. (ii) Non-renewable sources of energy like wood, coal, petroleum etc., have more demerits as compared to the renewable sources like sun, flowing water, windRead more
(i) So1ar energy and biomass energy- are two sources of energy which are considered as best form of energy from the environmental consequences.
(ii) Non-renewable sources of energy like wood, coal, petroleum etc., have more demerits as compared to the renewable sources like sun, flowing water, wind etc. Ii is because burning of fossil fuels cause pollution and more over these sources cannot be replenished at will.
(iii) The science teacher took this issue in today reference when our energy needs are increasing day by day and our fossil fuel resources are depleting at a fast rate. Moreorver, indiscriminate use of fossil fuels causes air, water and soil pollution which directly affects our health.
(a) The right hand thumb rule helps to determine the direction of magnetic field of straight current carrying conductor. According to this rule, hold the current carrying wire in your right hand such that the thumb is sketched along the direction of current. Then, the fingers will wrap around the wiRead more
(a) The right hand thumb rule helps to determine the direction of magnetic field of straight current carrying conductor. According to this rule, hold the current carrying wire in your right hand such that the thumb is sketched along the direction of current. Then, the fingers will wrap around the wire in the direction of the magnetic field.
(b) Fleming’s right hand rule is used to determine the direction of induced current in a conductor. It states that hold the forefinger, the central finger and the thumb of the right hand mutually perpendicular to each other such that the forefinger indicates the direction of magnetic field and the thumb is in the direction of motion of conductor. Then, the central finger shows the direction of current induced in the conductor.
When we touch a hot object; the body mechanism is such that it protects us from getting burnt. Hence, rather than to think about it, detects the heat and responds quickly. Reflex arc is such a connection that carries information about a stimulus through sensory nerves, to central nervous system/ i.eRead more
When we touch a hot object; the body mechanism is such that it protects us from
getting burnt. Hence, rather than to think about it, detects the heat and responds quickly. Reflex arc is such a connection that carries information about a stimulus through sensory nerves, to central nervous system/ i.e., spinal cord, which processes the information, sends message through another set of nerves, motor nerves, to the motor area (like muscle) to withdraw, thereby preventing us from any harm. Reflex arc are formed in the spinal cord itself although the information also goes on to reach brain where the encounter remains in the memory and make us a\ rare of our action. Secondly there are certain reflex actions under the control of brain known as cerebral reflex. Closure of eyes exposed to flash of light, salvation at sight or smell of food, peristalsis, inspiration and expiration are few examples of cerebral reflexes.
(i) In human heart ventricles have to pump blood to distant body parts, hence the pressure is much higher, as compared to auricles which pump blood to closer lungs. Hence, walls of ventricles are thicker. (ii) During breathing, even after forceful exhalation, gaseous exchange continues. This is becaRead more
(i) In human heart ventricles have to pump blood to distant body parts, hence the
pressure is much higher, as compared to auricles which pump blood to closer lungs. Hence, walls of ventricles are thicker.
(ii) During breathing, even after forceful exhalation, gaseous exchange continues. This is because small amount of air still remains in our lungs and hence diffusion continues.
(iii) In green plants during the day carbon dioxide is generated in respiration, but is not released out, as this carbon dioxide is used to make glucose during photosyntheesis
When we overeat, the burning sensation in the stomach is due to excess secretion of acid. An antacid can be used to nullify the effect of excess acid. For example, sodium bicarbonate acts as antacid by reacting with excess acid and increasing the pH i.e., adding an alkali.
When we overeat, the burning sensation in the stomach is due to excess secretion of acid. An antacid can be used to nullify the effect of excess acid.
For example, sodium bicarbonate acts as antacid by reacting with excess acid and increasing the pH i.e., adding an alkali.
Distinguish between kilowatt and kilowatt hour. For a heater rated at 4.4 kW; 220 Y calculate the (i) current drawn by the heater. (ii) resistance of the heater element. (iii) energy consumed by the heater in 5 hours. (iv) cost of running the heater if 1 kW h costs ₹ 6’50’
Distinction between kilowatt and kilowatt hour: kilowatt:- 1. It is a unit of electrical Power. 2. Power in kW = V(volt) x l(ampere)/1000 kilowatt hour:- 1. It is a unit of electrical energy. 2. Energy in kw h = v(volt)x l(ampere) x t(hour)/1000 As the heater is rated 4'4kW;220 V, hence (i) CurrentRead more
Distinction between kilowatt and kilowatt hour:
See lesskilowatt:- 1. It is a unit of electrical Power.
2. Power in kW = V(volt) x l(ampere)/1000
kilowatt hour:- 1. It is a unit of electrical energy.
2. Energy in kw h = v(volt)x l(ampere) x t(hour)/1000
As the heater is rated 4’4kW;220 V, hence
(i) Current drawn by the heater t = P/V = 4.4KW/220V = 4.4 x 1000W /220V = 20A
(ii) Resistance of the heater element R = V/I = 220V/20A = 11Ω
(iii) Energy consumed by the heater in 5 hours E =Pt = 4.4 kW x 5 h = 22 kw h
(iv) Cost of running the heater @ ₹ 6.50 per kw h=22 x ₹ 6.50 = ₹ 143
(a) State what happens when an acid reacts with a base? Name the reaction and give equation of the reaction involved. (b) Name one natural source of each of the following acids: (i) Citric acid (ii) Lactic acid. (iii) A student dropped a few pieces of marble in dilute Hydrochloric acid. The evolved gas passed through lime water. What change would be observed in lime water? Name the gas evolved.
(a) When an acid reacts with a base, formation of salt and water takes place. This is called neutralisation reaction. For example, sodium hydroxide reacts with hydrochloric acid as under: NaOH + HC1 ⟶ NaC1 + H₂O (b) (i) Citric acid - Lemon (ii) Lactic acid - Sour milk (curd) (iii) Marble is calciumRead more
(a) When an acid reacts with a base, formation of salt and water takes place. This is called neutralisation reaction. For example, sodium hydroxide reacts with hydrochloric acid as under:
See lessNaOH + HC1 ⟶ NaC1 + H₂O
(b) (i) Citric acid – Lemon
(ii) Lactic acid – Sour milk (curd)
(iii) Marble is calcium carbonate. Marble reacts with dilute hydrochloric acid to evolve carbon dioxide gas which when passed through lime water turns it milky. The reactions are as under:
CaCO₃ (s) + 2HCl (aq) ⟶CaC1₂ (aq) + CO₂ (g) + H₂O (1)
Ca(OH)₂ + CO₂ ⟶ CaCO₃ + H₂O
The gas evolved is carbon dioxide. Lime water will become milky.
(a) Define the term alloy. Write two advantages of making alloys. (b) Give reasons for the following: (i) Copper and aluminium wires are usually used for electricity transmission. (ii) An iron grill should be painted frequently.
(a) A mixture of two metals or a metal and a non-metal in a definite proportion is called alloy. Advantages of making alloys: (i) For making machinery parts. (ii) For making jewellery. (b) (i) Copper and aluminium are good conductors of electricity. Therefore, their wires are used for electricity trRead more
(a) A mixture of two metals or a metal and a non-metal in a definite proportion is
See lesscalled alloy.
Advantages of making alloys:
(i) For making machinery parts.
(ii) For making jewellery.
(b) (i) Copper and aluminium are good conductors of electricity. Therefore, their wires are used for electricity transmission.
(ii) Iron gets rusted by reaction with atmospheric oxygen and moisture. By painting frequently, iron grill is prevented from getting rusted.
State any three reasons to justify that LPG is considered an ideal fuel.
LPG is considered an ideal fuel on account of the following reasons: (i) The LPG has a large calorific value i.e., burning of even small quantity of LPG produces a large amount of heat energy. Thus, it is economical. (ii) It burns completely without any odour and leaves no residue. (iii) h is convenRead more
LPG is considered an ideal fuel on account of the following reasons:
See less(i) The LPG has a large calorific value i.e., burning of even small quantity of LPG produces a large amount of heat energy. Thus, it is economical.
(ii) It burns completely without any odour and leaves no residue.
(iii) h is convenient to use and easy to transport and store’
A science teacher asked his students of standard X to collect information about various energy sources and find how each one affects the environment. The teacher also motivated them to debate the merits and demerits of each source and select the best source of energy on that basis. Answer the following questions: (i) Mention two sources of energy based on their effect on environment which the students might have selected as the best. (ii) Which of the two energy sources renewable or non-renewable would have more demerits as compared to the other and why? (iii) Explain how the science teacher took this issue in today’ reference.
(i) So1ar energy and biomass energy- are two sources of energy which are considered as best form of energy from the environmental consequences. (ii) Non-renewable sources of energy like wood, coal, petroleum etc., have more demerits as compared to the renewable sources like sun, flowing water, windRead more
(i) So1ar energy and biomass energy- are two sources of energy which are considered as best form of energy from the environmental consequences.
See less(ii) Non-renewable sources of energy like wood, coal, petroleum etc., have more demerits as compared to the renewable sources like sun, flowing water, wind etc. Ii is because burning of fossil fuels cause pollution and more over these sources cannot be replenished at will.
(iii) The science teacher took this issue in today reference when our energy needs are increasing day by day and our fossil fuel resources are depleting at a fast rate. Moreorver, indiscriminate use of fossil fuels causes air, water and soil pollution which directly affects our health.
Name and state the rule: (a) which helps to determine the direction of magnetic field of straight current carrying conductor. (b) used to determine the direction of induced current.
(a) The right hand thumb rule helps to determine the direction of magnetic field of straight current carrying conductor. According to this rule, hold the current carrying wire in your right hand such that the thumb is sketched along the direction of current. Then, the fingers will wrap around the wiRead more
(a) The right hand thumb rule helps to determine the direction of magnetic field of straight current carrying conductor. According to this rule, hold the current carrying wire in your right hand such that the thumb is sketched along the direction of current. Then, the fingers will wrap around the wire in the direction of the magnetic field.
See less(b) Fleming’s right hand rule is used to determine the direction of induced current in a conductor. It states that hold the forefinger, the central finger and the thumb of the right hand mutually perpendicular to each other such that the forefinger indicates the direction of magnetic field and the thumb is in the direction of motion of conductor. Then, the central finger shows the direction of current induced in the conductor.
When we touch a hot object, how does our body mechanism protect us from getting burnt? State the role of the brain in reflex action.
When we touch a hot object; the body mechanism is such that it protects us from getting burnt. Hence, rather than to think about it, detects the heat and responds quickly. Reflex arc is such a connection that carries information about a stimulus through sensory nerves, to central nervous system/ i.eRead more
When we touch a hot object; the body mechanism is such that it protects us from
See lessgetting burnt. Hence, rather than to think about it, detects the heat and responds quickly. Reflex arc is such a connection that carries information about a stimulus through sensory nerves, to central nervous system/ i.e., spinal cord, which processes the information, sends message through another set of nerves, motor nerves, to the motor area (like muscle) to withdraw, thereby preventing us from any harm. Reflex arc are formed in the spinal cord itself although the information also goes on to reach brain where the encounter remains in the memory and make us a\ rare of our action. Secondly there are certain reflex actions under the control of brain known as cerebral reflex. Closure of eyes exposed to flash of light, salvation at sight or smell of food, peristalsis, inspiration and expiration are few examples of cerebral reflexes.
State reason for the following: (i) In human heart the walls of the ventricles are thicker than the auricles. (ii) During the breathing cycle even after forceful exhalation the exchange of gases continues. (iii) In green plants during the day carbon dioxide is generated in respiration but is not released out.
(i) In human heart ventricles have to pump blood to distant body parts, hence the pressure is much higher, as compared to auricles which pump blood to closer lungs. Hence, walls of ventricles are thicker. (ii) During breathing, even after forceful exhalation, gaseous exchange continues. This is becaRead more
(i) In human heart ventricles have to pump blood to distant body parts, hence the
See lesspressure is much higher, as compared to auricles which pump blood to closer lungs. Hence, walls of ventricles are thicker.
(ii) During breathing, even after forceful exhalation, gaseous exchange continues. This is because small amount of air still remains in our lungs and hence diffusion continues.
(iii) In green plants during the day carbon dioxide is generated in respiration, but is not released out, as this carbon dioxide is used to make glucose during photosyntheesis
Give one most suitable word {or the following statements: (i) Metal oxides which show basic as well as acidic behaviour. (ii) Some metals produce a sound on striking a hard surface.8
(i) Amphoteric oxides (ii) Sonorous (iii) Lustrous.
(i) Amphoteric oxides
See less(ii) Sonorous
(iii) Lustrous.
When we overeat we feel burning sensation in the stomach. State reason. Which substance can be used to nullify its effect? Give one example, state the property due to which we feel relief.
When we overeat, the burning sensation in the stomach is due to excess secretion of acid. An antacid can be used to nullify the effect of excess acid. For example, sodium bicarbonate acts as antacid by reacting with excess acid and increasing the pH i.e., adding an alkali.
When we overeat, the burning sensation in the stomach is due to excess secretion of acid. An antacid can be used to nullify the effect of excess acid.
See lessFor example, sodium bicarbonate acts as antacid by reacting with excess acid and increasing the pH i.e., adding an alkali.