Distance , d = a+b

The unit of d is in meter and t is in seconds.
So the unit of a a must be meter.
Now we have unit of b

is meter.
So unit of b*

= meter
Unit of b = meter/

So unit of a = m and unit of b = m/

.
Single
Displacement Reaction Definition. A
single displacement reaction is a chemical reaction where one reactant is exchanged for one ion of a second reactant. It is also known as a
single replacement reaction.
1. Frequency is the number of complete waves that pass a point in a second. 2.Wavelength is the distance between two crests or two troughs. 3.Time period <span> is the time it takes for one complete wave to pass a given point. 4. Amplitude is the height of the wave. Hence option 4 is correct. </span>
In some unusual applications of unusual components, I can think of unusual electric circuits where a switch may be connected in parallel with a device in order to control it.
But I'm sure this is not what's intended in a question on the high-school level.
Until you get in a situation with tricky applications in a tricky circuit, your switches will always be connect <em>in series</em> with the devices they control.