Who first traced the path of carbon in the biosynthetic phase? How did he do it?

Who did first introduced the concept of electric field?

Who first proposed that oxygen liberated in photosynthesis comes from water and not from carbon dioxide?

Who did proposed the first model of an atom.

Name the compound Calvin detected as the first product of photosynthesis. How many carbon atoms does it have?

In a primary school parents asked about of the number of hours they spend per day in helping their children to do home work. There were 90 parents who helped for frac(1)(2) hour to 1frac(1)(2) hours. The distribution of parents according to the time for which, they said they helped is given in the adjoining figure, 20% helped for the than 1frac(1)(2) hours per day, 30% helped for frac(1)(2) hour to 1 hours, 50% did not help at all. Using this, answer the following : How many said that they helped more than 1frac(1)(2) hours?

In a primary school parents were asked about of the number of hours they spend per day in helping their children to do home work. There were 90 parents who helped for frac(1)(2) hour to 1frac(1)(2) hours. The distribution of parents according to the time for which, they said they helped is given in the adjoining figure, 20% helped for more than 1frac(1)(2) hours per day, 30% helped for frac(1)(2) hour to 1 hours, 50% did not help at all. Using this, answer the following : How many said that they didnot help?

(a) A child stands at the centre of a turntable with his two arms outstretched. The turntable is set rotating with an angular speed of 40 rev/min. How much is the angular speed of the child if he folds his hands back and thereby reduces his moment of inertia to 2/5 times the initial value? Assume that the turntable rotates without friction. (b) Show that the child’s new kinetic energy of rotation is more than the initial kinetic energy of rotation. How do you account for this increase in kinetic energy?

Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientist of all times. What do you think did Einstein mean when he said “The most incomprehensible thing about the world is that it is comprehensible”.

Hasan buys two kinds of cloth materials for school uniforms, shirt material that costs him Rs 50 per metre and trouser material that costs him Rs 90 per metre. For every 2 meteres of the trousers material he buys 3 metres of the shirt materials. He sells the materials at 12% and 10% profit respectively. His total sale is Rs 36,660. How much trouser material did he buy?