CBSE ADDA

8 th   Mensuration CBSE Enrichment questions 1. A rectangular tank can hold 650 litres of milk . if it is 130cm long & 250cm wide , find the height of the tank. Solution:   Volume of   rectangular tank   = 650 litres = 650 × 1000 cm   3   = 650000 cm   3 We know that  Volume of a cuboid = l × b × h 650000 = 130 × 250 × h ⇒   h = (650000)/( 130 × 250 )= 20 cm Therefore, height of the tank = 20 cm 2. a hall is of length 16m , breadth 14m & height 5m . Calculate the no: of persons that can be accommodated in the hall , assuming 3.5m 3   of air is required for each person. Solution:   ∴ Volume of the hall = length × breadth × height                                                     = 16 × 14 × 5                                                       = 1120 m 3 Volume occupied my 1 man = 3.5 m 3 3.5 m 3    of air   occupied my 1 man 1120 m 3    of air   occupied my   (   1/3.5)x   1120= 320   man Therefore, n

Quest Time CBSE NCERT VI Chapter: Electric currents, Circuits, Cell. For Questions 1 to 10 visit link:  Class VI Physics By Jsunil 11. What conductors and insulators? Ans: The materials which allow electric current to pass through them are called conductors. Examples: All metals like Copper,Iron, Silver and Human body. INSULATORS: The materials which do not allow electric current to pass through them are called bad conductors or insulators. Examples: Plastic, Wood, Rubber and Glass. 12.   Why do electricians wear rubber gloves and shoes while at work? Ans: It because rubber gloves are an insulator and prevent current to flow in body .Thus saves electricians from electric shock. 13. What do you mean by heating effect of current? Ans: Electric current is actually the flow of electrons in the conducting material. Now, when these electrons flow, they encounter some resistance in the structure of the conductor, which accounts for the "resistance"

Brain Teaser Quest Time For Class 6th Light, Shadows And Reflections 1. How can you determine the length of the shadow of an object? Ans: We cannot correctly determine the length of the shadow of an object. The length of shadow depends on the angle at which light fall on a body and varies at different time of day. This principal helps us to make sun dial for calculating time. 2. How can you make sundial at home? Ans: We take a pencil and place it into the whole of the empty spool of thread.This work as sundial. Making the Sundial: 1. Using the pencil, poke a hole on the side of the paper / Styrofoam cup pproximately 2 inches below its top (rim). 2. Place the pebbles in the cup so to give it some weight and hold it upright.3. Cover the cup with the plastic lid. 4. Put the straw through the hole on the side of the cup and its lid while letting about half an inch of the straw stick out from the side. 4. Secure the straw to the cup by taping it down on the side.

Answer the following in one word 1. Light is form of what? Ans: Energy 2.What is the speed of light? Ans: 3 x10  8  m/s 3. Name the dark part of shadow? Ans: Umbra 4.What is lighter part of shadow known as? Ans: Penumbra 5. Are stars luminous or non luminous? Ans: Luminous _ Objects that give out or emit light of their own are called luminous objects like the sun 6. Do shadow depends on colour of objects? Ans: No 7. Which types of object allow light to pass partially? Ans: Translucent Answer the following in detail 8.What are transparent, translucent and Opaque objects. Give at least two example of each? Ans: If we cannot see through an object we call it Opaque like wood, plastic. Opaque object cannot allow  light to pass through.  If we can see through an object we call it transparent like glass, water and air .  Transparent objects allow   light to pass through .  If we can see through an object but not very clearly we call it

NCERT Solution, MCQs, Study Notes, Q & A 1.Define the term, functional group and give two examples for it.  Ans: An atom or a group of atoms on which properties of the carbon compound depends is known as functional group. Eg: - OH-            Alcoholic - CHO        Aldehydic - CO           Ketonic  - COOH     Carboxylic 2. Name the functional groups present in the following compounds. CH 3 CH 2 CH 2 -OH;  CH 3 CH 2 CH 2 COOH ; CH 3 -CH 2 -CHO;CH 3 COCH 2 CH 2 CH 3   Ans: CH 3 CH 2 CH 2 -OH          Alcoholic  CH 3 CH 2 CH 2 COOH     Carboxylic CH 3 -CH 2 -CHO              Aldehydic CH 3 COCH 2 CH 2 CH 3      Ketonic 3. Describe the preparation of ethanol by the fermentation process.  Ans: Fermentation of sugar is a process in which the sugar molecules are broken down in the ethylalcohol and carbon dioxide by the action of enzymes called invertage and zymase which are present in yeast. Molasses the bi-product of the sugar industry is mixed wi

  Class X NCERT Solution, MCQ's Study Notes, Q & A  Chapter 10 – Light - Reflection and Refraction Q.1.Why does a light ray incident on a rectangular glass slab immersed in any medium emerge parallel to itself? Ans: The extent of bending of the ray of light at the opposite parallel faces AB (air-glass interface) and CD (glass-air interface) of the rectangular glass slab is equal and opposite. This is why the ray emerges parallel to the incident ray.      OR, (The glass slab is rectangular and both sides of the glass slab have the same medium. The light refracts in such a way that incident and emergent rays are parallel.) Q.2.An object is placed at a distance of 10cm from a convex mirror of focal length of 15cm . Find the position and nature of the image Solution: Given :   f = +15cm          u = -10cm        v = ?’ 1/ f = 1/u +1/v   1/15 = -1/10 + 1/v 1/15 + 1/10 = 1/v 1/v = 1/6       v = 6cm Position of the image: Since V is formed at a distance o