CognitoQuiz

Soil Upper layer of earth crust, is called soil.  The mixture of rock particles and humus is called the soil.  Humus The rotting dead matter in the soil is called humus.  Weathering Formation of soil by break down of rocks by the action of winds, water and climate, is called weathering.  Nature of soil depends on The parent rock  Vegetation grows on it.  Wind, Climate, rainfall, temperature, light and humidity.  Soil profile  A vertical section through different layers of the soil is called soil profile.  Horizon Each layer of soil differing in texture, colour, depth, and chemical composition, is called horizon.  A-Horizon  It is dark in colour.  It is rich in humus.  Soil is fertile.  This layer is soft and porous.  This layer can retain more water.  It is also called top soil.  B-Horizon  This layer has lesser amount of humus.  This layer has more amount of minerals.  This l...

Wind Moving air is called wind.  Air exerts pressure.  High speed winds are accompanied by reduced air pressure.  Air moves from the region where the air pressure is high to the region where the pressure is low.  Why Smoke(warm air) goes up?  Generation of wind currents -Uneven heating between the equator and the pole  -Uneven heating of land and water   Monsoon winds carry water and it rains. 

Weather Temperature, rainfall, humidity, wind speed etc., of a place at a time is weather of that place.  Elements of weather Temperature Humidity Rainfall Wind speed etc.  The weather of a place changes day after day and week after week.  Maximum-Minimum thermometer Thermometer used to measure temperature of atmosphere, is called maximum-minimum thermometer.  The maximum temperature of the day - in afternoon.  The minimum temperature of the day- in early morning.  All changes in the weather are caused by the sun.  Climate The average weather pattern taken over a long time is called climate of the place.  Types of climate Hot and dry  Hot and wet Cold and dry  Cold and wet Adaptation Change in organism to cope changing environment, is called adaptation.  Polar regions These regions are covered with snow.  Climate- Very cold.  Day- 6months, Night-6months  Temperature- as low as -37°C. Animals present- Polar bear, ...

Physical properties Shape, size, colour and state of a substance are called its physical properties. Chemical properties Chemical composition of a substance are called its chemical properties. Kinds of changes -  (i) Physical changes  (ii) Chemical changes            OR  (i) Reversible changes (ii) Irreversible changes Physical changes  Changes in physical properties of a substance, is called physical changes.  Such change is reversible change.  No new substance is formed in such change. Example- Cutting of paper Chemical changes  Changes in chemical properties of a substance, is called chemical changes.  Such change is irreversible change.  New substance is formed in such change. Example- Burning of paper                   Burning of magnesium Few common Examples of Chemical changes   (i) Burning of magnesium ribbon    Magnesium + Oxygen -----> ...

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...

Topic of online quiz- Elements and their symbols No. of questions-10 Types of questions-MCQ Loading…

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...

Stars and Solar System Celestial objects The stars, the planets, the moons and many other objects in the sky are called celestial objects.  Full Moon Day  The day on which the whole disc of the moon is visible is known as full moon day.  New Moon Day On the fifteenth day after full moon day, the moon is not visible. This day is known as new moon day.  Crescent Moon  The moon whose only a small portion appears in the sky, is called crescent moon.  Phases of Moon  The various shapes of the bright part of the moon as seen during a month are called phases of moon.  The moon doesn't produce its own light.  We see the moon because, the sunlight falling on it gets reflected towards us.  The moon rotates on its axis.  The moon revolve around the Earth.  The moon has no atmosphere, no water,  Star The sun is also a star.  Sun appears larger than other stars. Because- -Stars are millions of times farther away than the sun....

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 ...