Questions

A number of possible explanations for why manhole covers are round include :

1. A round manhole cover cannot fall through its circular opening, whereas a square, rectangular, or oval manhole cover could fall in if it were inserted diagonally in the hole.

2. Circular covers don’t need to be rotated or precisely aligned when placing them on the opening.

3. A round manhole cover is easily moved and rolled.

4. Human beings have a roughly circular cross-section.

5. Round tubes are the strongest shape against the compression of the earth around them, so the cover of the tube would naturally be round as well.

6. It’s easier to dig a circular hole.

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped

The ATP is synthesized from ADP and an inorganic phosphate and involves special channel proteins that are embedded in a membrane. ATP is formed in the electron transport chain of photosynthesis and cellular respiration.

Photosynthesis only occurs in autotrophic organisms while respiration occurs in all types of organisms.

The only active volcano in India is situated in Andaman-Nicobar islands.

Mason Dixon Line

The mesosphere lies above the stratosphere and extends to an altitude of about 85 km. This is layer is often referred to as the cold layer, as the lowest readings in the atmosphere are found here.

Temperature decreases with height, reaching a minimum average value of -90 ºC at the top of the layer.