CBSE Revision Notes

CBSE Extra Questions for Class 7 Science

Extra Questions for Class 7 Science is very important resource for students preparing for the VII Board Examination. Here we have provided NCERT Exemplar Problems Solutions along with NCERT Exemplar Problems Class 7.

• Nutrition in Plants Class 7 Extra Questions
• Nutrition in Animals Class 7 Extra Questions
• Fibre to Fabric Class 7 Extra Questions
• Heat Class 7 Extra Questions
• Acids, Bases and Salts Class 7 Extra Questions
• Physical and Chemical Changes Class 7 Extra Questions
• Weather, Climate and Adaptations of Animals to Climate Class 7 Extra Questions
• Winds, Storms and Cyclones Class 7 Extra Questions
• Soil Class 7 Extra Questions
• Respiration in Organisms Class 7 Extra Questions
• Transportation in Animals and Plants Class 7 Extra Questions
• Reproduction in Plants Class 7 Extra Questions
• Motion and Time Class 7 Extra Questions
• Electric Current and Its Effects Class 7 Extra Questions
• Light Class 7 Extra Questions
• Water: A Precious Resource Class 7 Extra Questions
• Forests: Our Lifeline Class 7 Extra Questions
• Wastewater Story Class 7 Extra Questions

CBSE Pollution of Air and Water Class 8 Extra Questions

• Air pollution is the introduction into the atmosphere of chemicals, particulate matter, or biological materials that cause discomfort, disease, or death to humans, damage other living organisms such as food crops, or damage the natural environment or built environment
• Pollutants are the substance which contaminate air and water
• Major pollutants of air are carbon monoxide, nitrogen oxides, carbon dioxide, methane and sulphur dioxide. Please refer Pollution of Air and Water Class 8 Extra Questions for more information.

CBSE Stars and the Solar System Class 8 Extra Questions

• In the night sky there are moon, stars, planets and other celestial objects
• The phases of moon occur, because we are able to see only that part of the moon which reflects the light of the sun towards us
• Stars emit their own light. Sun is also a star, the distances of stars is expressed in light years
• Stars are present during the day time also but are not visible to us because of the bright sunlight. Please refer Stars and the Solar System Class 8 Extra Questions for more information.

CBSE Light Class 8 Extra Questions

• Light from an object enters our eyes then we see the objects around us
• Light is reflected from all surfaces
• Regular reflection takes place when light is incident on smooth, polished and regular surfaces
• Irregular reflection takes place from rough surfaces. Please refer Light Class 8 Extra Questions for more information.

CBSE Some Natural Phenomena Class 8 Extra Questions

• There are two types of charges namely positive and negative charge, like charges repel each other and opposite charges attract each other
• Some objects get charged by rubbing with other objects, the electrical charges produced by rubbing are called static charge
• Lightning in sky is caused by the accumulation of charges in the cloud
• Lightning strike could destroy life and property
• Electroscope is a device used to detect whether a body is charged or not. Please refer Some Natural Phenomena Class 8 Extra Questions for more information.

CBSE Chemical Effects of Electric Current Class 8 Extra Questions

• Materials which allow electric current to pass through them are good conductors of electricity and which does not allow electric current to pass through them are good conductors of electricity
• We should not experiment or play with the electrical appliances
• Some liquids are good conductor of electricity and some are bad conductors of electricity
• Most liquids that conduct electricity are solutions of acids, bases and salts
• The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating. Please refer Chemical Effects of Electric Current Class 8 Extra Questions for more information.

CBSE Sound Class 8 Extra Questions

• Sound is a sequence of waves of pressure that propagates through compressible media such as air or water
• Sound is produced by vibrating objects
• Sound helps us to communicate with one another, we can hear a variety of sounds in our surrounding
• The to and fro and back and forth motion of an object is called vibration
• In human sound is produced by the voice box or larynx. Please refer Sound Class 8 Extra Questions for more information.

CBSE Friction Class 8 Extra Questions

• Friction is the “evil” of all motion. No matter which direction something moves in, friction pulls it the other way
• Friction is caused by the irregularities on the two surfaces in contact
• Friction depends on nature of surfaces in contact
• Friction depends on how hard the two surfaces press together. Please refer Friction Class 8 Extra Questions for more information.

CBSE Friction Class 8 Extra Questions

• Friction is the “evil” of all motion. No matter which direction something moves in, friction pulls it the other way
• Friction is caused by the irregularities on the two surfaces in contact
• Friction depends on nature of surfaces in contact
• Friction depends on how hard the two surfaces press together.
• Static friction comes into play when we try to move an object at rest
• Sliding friction comes into play when an object is sliding over another. Please refer Friction Class 8 Extra Questions for more information.

CBSE Force and Pressure Class 8 Extra Questions 

• A push or a pull on an object is called a force.A force arises due to the interaction between two objects.
• Force has magnitude as well as direction.
• Force may change in the state of motion of an object or it may bring about a change in the shape of an object. Please refer Force and Pressure Class 8 Extra Questions  for more information.