NCERT solutions for Science

 NCERT solution >   Class 9 > Science . NCERT solution for class 9//  Science // Chapter 11 --Work and energy Chapter 11- Work and energy  Page number 148. Q1. A force of 7 N on an object the displacement is say 8 m in the direction of the force let us take it that the force acts on the object through displacement what is the work done in this case. Answer-   Force , F = 7 N  Displacement S = 8m . Work W = F x S  W = 7 x 8  = 56 Nm.  Page number 149 . Q2. When do we say that work is done? Answer- When the force is applied and object and object moves through a distance in the direction of applied force then we say that work is done  It is equal to the product of force and displacement  W = F x S  Q3. Write an expression for the work done when a force is acting on an object in the direction of its displacement?  Answer- When a force F is applied on a body and it moves the body by distanc...

  NCERT solution > Science > class 6  NCERT solution for class 6 // Science // Chapter 11- Light shadows and reflections  Chapter 11-  Light shadows and reflections. Exercise  Q1. Rearrange the boxes given below to make a sentence that help us understand opaque objects . OWS.    AKE.      OPAQ.     UEO.      BJEC.   TSM.   SHAD  Answer - OPAQUE OBJECTS MAKE SHADOWS Q2. Classify the objects of materials given below as Opaque, transparent or translucent and luminous or non luminous  . Air ,water ,a piece of Rock, a sheet of aluminium a mirror, a wooden board ,a sheet of polythene ,a CD, smoke ,a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall ,sheet of carbon paper ,the flame of gas burner, a sheet of cardboard ,a lighted torch, a sheet of cellophane , a wire mesh , kerosene stove ,Sun ,Firefly ,moon . Answer .  Opaqu...

  NCERT solution  > class 7 > Science  Chapter 18  - Wastewater story  Exercise  Q1. Fill in the blanks  1. Cleaning of water is a process of removing pollutants 2. Wastewater released by houses is called sewage . 3. Dried sludge is used as manure . 4. Drains get blocked by cooking oil and fats Q2. What is sewage explain why it is harmful to discharge untreated sewage into rivers or seas?  Answer - Sewage is the waste water containing both liquid and solid impurities from homes, industries, hospital, officers it contain the various contamination include disease-causing bacteria organic and inorganic waste etc. If untreated sewage is discharged into rivers or sea then it polluted the water and unsafe for drinking it also can cause Cholera typhoid and dysentery like disease so it is harmful to discharge untreated sewage into the rivers or sea Q3. Why should oils and fat be not released in the drain explain. Answer - oil and fats deposited o...

 NCERT solution  > class 6 >  science  NCERT solution for class 6 // Science  // Chapter 12 -  Electricity and circuits Chapter 12  - Electricity and circuits  Q 1. Fill in the blanks   a) The device that is used to break an electric circuit is called switch  b) An electric cell has  Two terminals . Q2. Mark true or false for following statements. a) Electric current can flow through metals. b) Instead of metal wires a jute steering can be used to make a circuits.  c) Electric current can pass through a sheet of thermocol. Answer - a) True b) False.  c) false .  Q3. Explain why the bulb would not glow in the arrangement shown in figure     Answer- T he bulb would not glow in the arrangement shown in figure because the screwdriver attached in that arrangement has a handle of plastic and plastic is the insulator of electricity Q4. Complete the drawings shown in figure to indicate where the fre...

 NCERT solution   > Science  > Class 8  NCERT solution for class 8  // Science // chapter 13 - Sound Chapter 13 - Sound  Exercise  Q1. Choose the correct answer  1. Sound can travel through  a) gases only     b ) Solid only     c) liquid only   d) solid liquid and gases    2. Voice of which of the following is likely to have minimum frequency. a) baby girl .    b)  baby boy     c) a man    d) a woman   3. In the following statement tick  T against those which are true and F against those which are false . a) sound cannot travel in vacuum . b) The number of oscillation per second of A vibrating object is called its time period. c) If the amplitude of vibration is largest sound is feeble . d) For human ears the audible range is 20 Hz to 20000 Hz . e) The lower the frequency of vibration the higher is the pitch. f) Unwanted or unpl...

  NCERT solution >  Class 7 >  Science  NCERT solution for class 7// Science  // Chapter 17 -   Forest our lifeline Chapter 17 -   Forest our lifeline  Exercise  Q1. Explain how animals dwelling in the forest help it grow and regenerate.?  Answer-  I n forest the animals are various types they may be herbivorous carnivorous omnivorous and microorganisms all they play important role in the maintaining of food chain  Microorganism convert the dead plants and animals into humus and return back the nutrients into the soil  Animals also help in the dispersing of seed of some plants  The animal waste material also provide the nutrients to the soil all these activities of animals dwelling in the forest help to grow and regenerate Q2. Explain how forests prevent floods?  Answer-   The roots of the forest trees hold the soil particles and they are also helpful for the seepage of water inside it and re...

 NCERT solution  > class 7 > Science  NCERT solution class 7 >  Science  > chapter 16 -  Water a precious resource Chapter 16  -Water a precious resource. Q1. Mark T if the statement is true and F if it is false. a) The freshwater Stored in the ground in much more than that present in the rivers and lakes of the world . b) Water shortage is a problem faced only by people living in rural areas. c) Water from rivers is the only source for irrigation in the fields. d) Rain is ultimate source of water  Answer - a) True   b) false   c) false.  d) true  Q2. Explain how groundwater is recharged?  Answer- Rain water and water present in the water bodies is percolate into the soil by the process of infiltration and then that infiltrated water accumulated in aquifer deep under the soil and in this way it recharge the groundwater Q3. There are 10 tube Wells in a lane of 50 houses what could be the  long-te...