Question Text
Question 4 :
Magnesium ribbon burns to form ________ and produces heat and light
Question 5 :
Is it True or false that greater the calorific value, better is the fuel?
Question 8 :
On placing an inverted tumbler over a burning candle, the flame extinguishes after some time. This is because of non- availability of
Question 10 :
The sources of heat energy for domestic and industrial purposes are called _____
Question 12 :
The calorific values of petrol and CNG are 45000 kJ/kg and 50,000 kJ/kg, respectively. If you have vehicle which can run on petrol as well as CNG, which fuel will you prefer, why?
Question 13 :
What cools the combustible material so that its temperature is brought below its ignition temperature?
Question 17 :
State true or false. Calorific value of wood is higher than that of coal.
Question 18 :
The conditions under which combustion can take place is/are (i) Presence of fuel (ii) Air (or oxygen) (iii) Ignition temperature
Question 19 :
The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its______value.
Question 20 :
Gas burns rapidly and produces heat and light. Such combustion is known as-
Question 21 :
Which zone of a flame does a goldsmith use for melting gold and silver?
Question 22 :
Is it essential for a substance to reach ignition temperature to burn?
Question 24 :
Is it True or false that increased concentration of nitrogen in air is believed to cause global warming?