Environment & science (class VIII) Some questions

 1. Fill up the gaps with following words 

( Liquid, decreases, calorie, melting, mass)

i) The amount of heat required for increasing the temperature of a body depends on ............

ii) The unit of heat is ...............

iii) The change of state from solid to ..........is called  -------.

iv) If the pressure decreases the boiling point of a liquid _-------------.

2. 

a) Write the name of a substance that is non conductor of electricity . 

b) What is the name of the electrode that is connected to the positive end of of the battery ?

c) What is the name of the electrode that is connected to the negative end of the battery ? 

d) Which material would you use for gold plating of a metal at the anode and at the cathode ? 

3. Answer the following .

a) 2 H₂O₂ = 2H₂O + O₂ , Name the catalyst of the reaction . 

b) During exothermic reaction , the energy is ------------.

c) During oxidation -----------------reacts with a compound .

d) Identify the oxidation & reduction reaction 

i) Fe³⁺ +e = Fe²⁺ 

ii) Cl⁻ = Cl + e 

Answer : 

1. i) mass ii) calorie iii) liquid , melting iv) decreases 

2.a) plastic , wood ,glass etc  b) Anode c) Cathode d) The material on which gold is to be coated is used as cathode and gold is used as anode .

3. a) manganese dioxide ( MnO₂ ) b) released c) oxygen  d) i) reduction ( electron is accepted) ii) oxidation ( electron released ) 

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MCQ for H.S

 1. A chemical cell of emf  E and internal resistance r is connected to a resistance R .The potential difference across R is given by :  A) ...