CognitoQuiz

Acids The chemicals causing sourness of substance, is called acids .  These are not soapy to touch.  These turn blue litmus into red.  Example- Acetic acid(chemical in vinegar)  Bases The chemicals causing bitterness of substance, is called bases .  These are soapy to touch.  These turn red litmus into blue.  Example- baking soda, calcium hydroxide etc.  Indicator The substance used to test whether a substance is acidic or basic, are called indicator.  Example- Turmeric, litmus, china rose petals, phenolphthalein etc.  Litmus:A natural dye It is a natural indicator.  It is extracted from lichen.  When added to acid, it turns red.  When added to base, it turns blue.  Available in- Solution form, Paper strips Neutral solution The solution which donot change the colour of either red or blue litmus, is known as neutral solution.  Example- Sugar solution, water etc.  China rose as indicator China rose indicator t...

Heat Energy that increases hotness of an object.  Temperature A reliable measure of the hotness of an object, is its temperature .  Thermometer A device used to measure temperature, is called thermometer .  Types of thermometer (i) Clinical thermometer (ii) Laboratory thermometer (iii) Maximum-minimum thermometer Clinical thermometer -The thermometer used to measure temperature of body, is called clinical thermometer.  -It consists of- glass tube,                           Bulb                           Mercury thread                           Kink -Range- 35°C to 42°C. -It has kink.  Clinical thermometer Laboratory thermometer -The thermometer used to measure temperature of an object, is c...

What Makes Things Visible   When light from an object enters our eyes, then we see the object.  The light may have been emitted or reflected by the object.  Mirror   Highly polished surface is called mirror.  Reflection Bending back of light ray after falling on a surface, is called reflection.  Incident ray The light ray which strikes any surface, is called incident ray.  Reflected ray  The ray that comes back from the surface after reflection, is called as reflected ray.  Normal Line perpendicular to surface at point of incidence of light ray, is called normal.  Angle of incidence The angle between normal and incident ray, is called angle of incidence.  Angle of reflection The angle between normal and reflected ray, is called angle of reflection.  Laws of reflection (i) The incident ray, the normal at the point of incidence and the reflected ray, all lie in the same plane.  (ii) The angle of incidence is always equal to ...

Good Conductor The substance through which electricity can pass is called good conductor.  Examples - Copper, Aluminum Poor conductor The substance through which electricity can not pass is called poor conductor. Examples - Rubber, plastic etc.  Tester A device that test conductance of a substance, is called tester.  Solutions of acids, bases and salts are generally good conductor.  Chemical effects of Current Chemical reactions (effects) caused when electricity passes through a conducting liquid, is chemical effects of current.  How to recognize chemical reaction - Release of gas - Change of colour of solution - Release of heat - Formation of new substance In battery No. of terminals- 2 (positive and negative)  Positive terminal is also called Anode .  Negative terminal is also called cathode .  Solution  is called electrolyte .  Passing current through a solution ...

Friction The force that opposes the relative motion between two surfaces in contact, is called friction.  Factors affecting friction Weight of object  Nature of surfaces in contact More the weight of object, more the friction.  More smooth surface experience less friction.  Importance of friction Friction helps in stopping object Friction helps to write, walk,  Friction helps in all activities Friction produces heat.  Harm cause by Friction Sole of shoes wear out.  Machine parts get wear out.  Friction can be increased by making surfaces rough. ( More rough means more interlocking between surfaces which means more friction )  Friction can be decreased by applying lubricant on surfaces.  Friction can be decresed by changing shape of object.  Rolling friction The force that oppose motion of rolling object, is rolling friction.  Sliding friction The force that oppose moti...

Force   The push or pull of an object, is called force.  Forces are due to interaction between objects.  Force applied on an object in the same direction add to each other.  Force applied on an object in opposite directions substract each other.  The strength of force is measured by its magnitude.  A force can change the state of motion of an object.  Change in state of motion jeans Rest to motion Motion to rest  Increase in speed  Decrease in speed Force on an object may change its shape.  Types of forces   Contact force   The force that can be applied only by touching object,is called contact force.  Non-Contact force   The force that can be applied without touching object,is called contact force.  Muscular force   The force resulting due to action of muscles is called muscular force.  Friction The force that oppose motion of an object.  Magnetic force The force exerted by a magnetic material is ...

Reaching the Age of Adolescene  Adolescene The period of life, when the body undergoes changes , leading to reproductive maturity, is called adolescene.  Period - age of 11 to age of 19. Also called " teen age ". Because this period covers the teen ages i.e, 13 to 19  Adolescene may begin earlier in girls than boys.  Puberty Period during adolescene, when human body undergoes several changes, is called puberty.  Important change - Boys and girls become capable of reproduction.  Changes at puberty   Increase in height  Change in body shape  Change in voice  Increased activity of sweat and sebaceous glands  Development of sex organs  Reaching mental, intellectual and emotional maturity Changes in Girls   Increase in height Region below the waist becomes wider  Less growth of muscles  Voice becomes high pitched.  Increased activity of sweat and sebaceous glands Ovaries enlarge.  Eggs begin to mature....

Combustion and Flame  * Combustion - - Combustion is a chemical process. - In combustion, substance reacts with oxygen. - Heat is given off.    Substance + Oxygen ----> Heat - Example- Burning of paper or Magnesium * Combustible substance or fuel - - The substance that undergoes combustion, is called combustible substance . - Example- Paper. * Non-combustible substance - - The substance that doesn't undergo combustion, is called non-combustible substance. - Example- Stone * Ignition temperature Lowest temperature at which  a substance catches fire is called its ignition temperature. * Ignition temperature of wood is greater than that of kerosene. So, kerosene burns first and wood later. Lower ignition temperature -----> Burns faster. * Conditions necessary for combustion (a) Combustible substance - -Substance that can be burnt. -Example- Paper (b) Combusting Substance -Substance that helps in combustion, i.e. oxygen. (c) Igniti...

Materials: Metals and Non-metals * Lustre -    Lustre is physical property of substance by    which it looks shiny. * Malleability -    Malleability is property of metal, by which    they can be beaten into thin sheets. * Ductility -    Property of metal, by which they can be    drawn into wires, is called ductility. * Good conductor of heat/electricity    -The materials through which heat/electricity    can pass, is called good conductor of    heat/electricity.    -Example- Iron. * Poor conductor of heat/electricity    -The materials through which heat/electricity      cannot pass, is called poor conductor of      heat/electricity.    - Example- Plastic * Sonorous -    Metals are sonorous since they produce    ringing sound. * Physical properties of metals and Non-    metals ...

  Synthetic Fibres and Plastic-                   Summary         NCERT CBSE CLASS 8 SCIENCE * Fibres -        -Very thin thread        - Thread is prepared from it. * Fibres ----> Thread/Yarn---->Fabric/Cloth---->             ---->Dress * Types of Fibres -      (a) Natural fibres -       -Fibres that are obtained from plants or         animals, is called natural fibres.       -Examples- Cotton, Jute, Silk, Wool      (b) Artificial/Synthetic fibres-        -Fibres that are not obtained from plants         or animals, is called synthetic fibres.       -Examples- Rayon, Nylon, Acrylic,                         ...

Microorganisms- Our friend and Foe  NCERT CBSE CLASS VIII Science Chapter 2  This test contains 10 multiple choice questions each carrying 2 marks.  You have to fill your details first and then attempt answer.  After attempting answers, click on submit.  Don't forget to click on "view your score'' after submission of answers.  Best of luck.  Loading…

Fibre to Fabric  NCERT CBSE Class 7 Online Test/Quiz for Fibre to Fabric  Online test for "fibre to fabric" consists of ten questions, all having four alternatives. You have to choose the correct option. After attempting all questions, enter your name, class, roll no and email id. Email id is asked because through that results will be share to you.  And at last don't forget to submit your answers. After submission you can see your results too.  Enjoy taking test.  Topic- Fibre to Fabric NCERT CBSE Science Class 7 Loading…

Nutrition in Plants NCERT CBSE Class 7 Chapter 1 Summary Note                    Nutrition in Plants  *Nutrition     -Intake of foods and its utilisation by our        body.  *Mode of nutrition              (a)Autotrophic nutrition              (b)Heterotrophic nutrition *Autotrophic nutrition     -Mode of nutrition where organism prepare       its food themselves.      -(Auto- Self, trophic- Nourishment)  *Heterotrophic nutrition     -Mode of nutrition where organism depend       on other for food.      -(Hetero- other, trophic- nourishment)  *Photosynthesis     - Preparation of food by green plants.      - Use CO2 and water.      - Prepare ...

NCERT CBSE Class 7 Chapter 2 Exercise Solution Nutrition in Animals  NCERT Class VII Chapter-2 1. Fill in the blanks: (a) The main steps of nutrition in humans are __________, __________,__________, _________ and __________. Answer- Ingestion, digestion, absorption, assimilation, egestion.  (b) The largest gland in the human body is __________. Answer- liver.  (c) The stomach releases hydrochloric acid and ___________ juices which act on food. Answer- gastric (d) The inner wall of the small intestine has many finger-like outgrowths called _________. Answer- Villi.  (e) Amoeba digests its food in the ____________ . Answer- Food vacuole.  2. Mark ‘T’ if the statement is true and ‘F’ if it is false: (a) Digestion of starch starts in the stomach. (T/F) Answer- F Correct statement- Digestion of starch starts in the mouth.  (b) The tongue helps in mixing food with saliva. (T/F) Answer- T (c) The gall bladder tempora...

Microorganisms:Friends or Foe NCERT Class VIII chapter 2(Science)  Loading…