Questions

Metamorphism is the change of minerals or geologic texture in pre-existing rocks, without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids.

The parent rock must be in solid form. Tons of pressure must be applied for metamorphism to happen. The process must take place underground.

Hubs regenerate electrical signals, which are specified at the Physical layer.

A rift valley is formed either due to upheaval of blocks on either sides of a fracture or due to subsidence of block between them.

Tetraethyl lead is a highly toxic compound used as a gasoline additive.

Tetraethyl lead abbreviated as TEL, is an organo lead compound with the formula (CH₃CH₂)₄Pb. It is a petro-fuel additive which in turn caused increased vehicle performance. This is also used as an antiknock agent in gasoline and jet fuels. Tetraethyl lead is absorbed rapidly by the skin, the lungs, and the gastrointestinal tract. It is converted to triethyl lead, which might be responsible for its toxicity.

It takes 248 yrs for Pluto to orbit the Sun.