Answer:
D) Synthesizers have always had a well-established presence in standard ensembles
Explanation:
As synthesizers are electronic music instruments that can create the sounds of many different musical instruments, they have been seen as a threat to many musicians since their invention.
I think it’s B open series circuit but I’m not sure
Answer:
n = 1.42
Explanation:
The refractive index for a medium is given by the ratio of the speed of light in vacuum to the speed of light in a medium.

So, the refractive index of the medium is 1.42.
Temperature is just a measure of how HOT or COLD a substance is, which can be easily defined by a magnitude using a numerical value say “300 K” or “27°C”. Hence we can say it is a scalar quantity.
But the energy which transfer by virtue of a temperature difference is a vector quantity, as it has both magnitude and direction of motion (from High temperature to low temperature region).