When the material P mined from the earth is heated strongly in an insufficient supply of air, it produces a solid fuel Q which mainly consist of carbon. When another material R obtained from trees is heated in an insufficient supply of air, it produces another solid fuel S which also consists mainly of carbon. Then, which of the following is true?

100 W/m² of solar energy is received by the Earth. If all the energy was to be absorbed by a bucket of water (mass 30 kg) in 30 minutes, then the rise in temperature of water will be

While filling LPG in cylinders, a substance X is added to make the detection of leakage of LPG from the cylinder easy. The substance X is

For a nuclear reactor, 48 kJ of energy is produced per minute. If the energy released per fission is 3.2 × 10^-11 J, then the number of fission which would be taking place in a reactor per second is

The mass number of four different elements A, B, C and D are 2, 35, 135 and 239, respectively. Which of them would provide the most suitable the most suitable for nuclear fission?