CBSE | NCERT CLASS

 Chemical effect of electric current: part 2 25. Sugar solution does or does not conduct electricity. Answer: sugar solution does not conduct electricity. 26. A torch bulb cannot be used to detect weak electric current flowing through a liquid in a circuit .............why? Answer: the current in the circuit may be weak if the the electrical conductivity of the liquid we are testing is very low. So, if we test a liquid hav*ZzzZing very low electrical conductivityz by using a torch bulb in the circuit , then the bulb may not glow at all. Because too week current flowing through it. Show a torch bulb cannot be used to detect with electric current flowing through a liquid in a circuit. 27. How do we detect electric current flowing through liquids? Answer: the with electric current flowing through liquids having low electrical conductivity can be detected in two ways: i) by using a LED ii) by using a compass. 28. Write the full form of "LED". Answer: light emitting diode. 29. Ho

  1 . define good conductor of electricity? Give example. Answer: the materials which allow electric current to pass through them easily are called good conductors of electricity or simply conductors of electricity.  Example:  generally metals are good conductor of electricity such as copper aluminium etc.  2.   define bad contactor of electricity. Give example.  Answer:  the materials which do not allow electric current to pass through them easily are called bad conductor of electricity.  Example:  the materials such as rubber plastic and wood are example of bad conductor of electricity.  3. Name some liquids which can conduct electricity.  Answer: solution of acid,  solution of base, salt in water.  A solution of of sulphuric acid,  hydrochloric acid,  aur any other acid in water conducts electricity.  A solution of sodium hydroxide, potassium Hydroxide or any other soluble base in water conduct electricity. A solution of copper sulphate, common salt or any other salt in water also

Sound Physics Class 8 : CBSE solved paper with question , helps in solve NCERT problem . Question 1:  name the factor on which pitch of a sound depend? Explain giving some examples. Answer:   Pitch of sound depend on frequency. If the frequency of vibration is more than  the produce sound has a higher pitch. If the frequency of vibration is lesser, than the produce sound has a lower pitch. Women sound is shriller than man because sound of women has higher frequency then a man.

Q1. All animals finally die, yet the species survives. Give reasons for this. Answer : All type of animals during his life span reproduce and produce young ones (offspring). Hence, even after they die, the species still exist on earth.

Q1. Why is it comfortable to lift a school bag with broad straps than thin straps? Answer: Pressure is inversely proportional to area. Since broader straps have greater area, so, the pressure decreases.