Which material is used in controlling chain reaction in a nuclear reactor?

The per unit voltages of two synchronous machines connected through a lossless line are $$0.95\,\angle {10^ \circ }$$ and $$1.0\,\angle {0^ \circ }.$$ Match the two sides in the following

If the reference bus is changed in two load flow runs with same system data and power obtained for reference bus taken as specified P and Q in the latter run

A periodic rectangular signal, $$x(t)$$ has the waveform shown in Figure. Frequency of the fifth harmonic of its spectrum is