Which of the following statements is/are false? (P) Manganese is used as scavenger in making steel. (Q) All known isotopes of technetium are radioactive, except ⁹⁸Tc. (R) Rhenium is used in making electric furnace windings and spectrophotometer filaments.

(P) Manganese is an important additive in steel making and acts as a scavenger as it has the property of removing both oxygen and S and thus preventing bubbles and brittleness. (Q) Technetium (⁹⁹Tc) was the first man-made element with radioactive property. All known isotopes of technetium (includes ⁹⁷Tc, ⁹⁸Tc) have radioactive property. It is one of the fission products of uranium. It obtained by spent fuel rods in nuclear reactors. (R) Rhenium is used in making electric furnace windings and spectrophotometer filaments due to its very high melting point (3180^oC).