Addition of high proportions of manganese makes steel useful in making rails of rail-roads because manganese

The molar mass of the water-insoluble product formed from the fusion of chromite ore $(FeCr_2O_4)$ with $Na_2CO_3$ in the presence of $O_2$ is $..........$ $g \ mol^{-1}$.

The important advantage$(s)$ of Lintz and Donawitz $(L.D.)$ process for the manufacture of steel is (are):

Which among the following is an alloy of antimony,tin and copper?

Given below are two statements:
Statement $I$: During electrolytic refining,the pure metal is made to act as anode and its impure metallic form is used as cathode.
Statement $II$: During the Hall-Heroult electrolysis process,purified $Al_2O_3$ is mixed with $Na_3AlF_6$ to lower the melting point of the mixture.
In the light of the above statements,choose the most appropriate answer from the options given below:

Brass is an alloy of copper and ......... .