Select the correct use of the compound tms in nmr spectroscopy. a. it is a signal-to-noise enhancerb. it is an internal standard for signal strengthc. it is a commonly used solvent for samplesd. it is an internal standard for chemical shifts

TMS stands for Tetramethylsilane

Formula : Si(CH₃)₄

It is used as internal standard for chemical shift

In TMS all the four methyl groups are similar thus all the 12 hydrogen are chemically equivalent. They will show proton NMR at same level and which will appear as a singlet.

We have defined this singlet to be as reference set as zero.

Generally the other organic compounds show chemical shift downfield.So have positive chemical shift with respect to TMS shift.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.